diff --git a/lab4/zad3/.gitignore b/lab4/zad3/.gitignore
new file mode 100644
index 0000000..eb5a316
--- /dev/null
+++ b/lab4/zad3/.gitignore
@@ -0,0 +1 @@
+target
diff --git a/lab4/zad3/Cargo.lock b/lab4/zad3/Cargo.lock
new file mode 100644
index 0000000..448d0c4
--- /dev/null
+++ b/lab4/zad3/Cargo.lock
@@ -0,0 +1,87 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "cfg-if"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
+
+[[package]]
+name = "getrandom"
+version = "0.2.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c4567c8db10ae91089c99af84c68c38da3ec2f087c3f82960bcdbf3656b6f4d7"
+dependencies = [
+ "cfg-if",
+ "libc",
+ "wasi",
+]
+
+[[package]]
+name = "libc"
+version = "0.2.155"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "97b3888a4aecf77e811145cadf6eef5901f4782c53886191b2f693f24761847c"
+
+[[package]]
+name = "libgen"
+version = "0.1.0"
+dependencies = [
+ "rand",
+]
+
+[[package]]
+name = "libtree"
+version = "0.1.0"
+
+[[package]]
+name = "ppv-lite86"
+version = "0.2.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5b40af805b3121feab8a3c29f04d8ad262fa8e0561883e7653e024ae4479e6de"
+
+[[package]]
+name = "rand"
+version = "0.8.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "34af8d1a0e25924bc5b7c43c079c942339d8f0a8b57c39049bef581b46327404"
+dependencies = [
+ "libc",
+ "rand_chacha",
+ "rand_core",
+]
+
+[[package]]
+name = "rand_chacha"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e6c10a63a0fa32252be49d21e7709d4d4baf8d231c2dbce1eaa8141b9b127d88"
+dependencies = [
+ "ppv-lite86",
+ "rand_core",
+]
+
+[[package]]
+name = "rand_core"
+version = "0.6.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ec0be4795e2f6a28069bec0b5ff3e2ac9bafc99e6a9a7dc3547996c5c816922c"
+dependencies = [
+ "getrandom",
+]
+
+[[package]]
+name = "wasi"
+version = "0.11.0+wasi-snapshot-preview1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9c8d87e72b64a3b4db28d11ce29237c246188f4f51057d65a7eab63b7987e423"
+
+[[package]]
+name = "zad3"
+version = "0.1.0"
+dependencies = [
+ "libgen",
+ "libtree",
+]
diff --git a/lab4/zad3/Cargo.toml b/lab4/zad3/Cargo.toml
new file mode 100644
index 0000000..b9aeadd
--- /dev/null
+++ b/lab4/zad3/Cargo.toml
@@ -0,0 +1,8 @@
+[package]
+name = "zad3"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+libgen = { path = "../../libgen" }
+libtree = { path = "../../libtree" }
diff --git a/lab4/zad3/src/main.rs b/lab4/zad3/src/main.rs
new file mode 100644
index 0000000..e6a7f0d
--- /dev/null
+++ b/lab4/zad3/src/main.rs
@@ -0,0 +1,34 @@
+use libgen::{gen_asc, gen_rand};
+use libtree::RedBlackTree;
+
+fn main() {
+    println!("1. insert 50 ascending; delete 50 random");
+    let mut tree1 = RedBlackTree::new(50);
+
+    for i in gen_asc(50) {
+        println!("insert {i}");
+        tree1.insert(i);
+        println!("{}", tree1);
+    }
+
+    for i in gen_rand(50) {
+        println!("delete {i}");
+        tree1.delete(i);
+        println!("{}", tree1);
+    }
+
+    println!("2. insert 50 random; delete 50 random");
+    let mut tree2 = RedBlackTree::new(50);
+
+    for i in gen_rand(50) {
+        println!("insert {i}");
+        tree2.insert(i);
+        println!("{}", tree2);
+    }
+
+    for i in gen_rand(50) {
+        println!("delete {i}");
+        tree2.delete(i);
+        println!("{}", tree2);
+    }
+}
diff --git a/libtree/src/lib.rs b/libtree/src/lib.rs
index bf08b62..ccae51a 100644
--- a/libtree/src/lib.rs
+++ b/libtree/src/lib.rs
@@ -1,6 +1,8 @@
 mod binary_search_tree;
+mod red_black_tree;
 
 pub use binary_search_tree::*;
+pub use red_black_tree::*;
 
 #[derive(Clone, Default)]
 pub struct Stats {
diff --git a/libtree/src/red_black_tree.rs b/libtree/src/red_black_tree.rs
new file mode 100644
index 0000000..c41814a
--- /dev/null
+++ b/libtree/src/red_black_tree.rs
@@ -0,0 +1,540 @@
+use std::{cmp::Ordering, fmt::Display, ptr};
+
+#[derive(Clone, Copy, PartialEq)]
+pub enum Colour { Red, Black }
+
+#[derive(Clone)]
+pub struct RedBlackTreeNode {
+    key: u64,
+    colour: Colour,
+    left: RBT,
+    right: RBT,
+    parent: RBT,
+}
+
+struct RBT(*mut RedBlackTreeNode);
+
+impl Clone for RBT {
+    fn clone(&self) -> Self {
+        Self(self.0)
+    }
+}
+
+impl Copy for RBT {}
+
+impl Ord for RBT {
+    fn cmp(&self, other: &RBT) -> Ordering {
+        unsafe { (*self.0).key.cmp(&(*other.0).key) }
+    }
+}
+
+impl PartialOrd for RBT {
+    fn partial_cmp(&self, other: &RBT) -> Option<Ordering> {
+        unsafe { Some((*self.0).key.cmp(&(*other.0).key)) }
+    }
+}
+
+impl PartialEq for RBT {
+    fn eq(&self, other: &RBT) -> bool {
+        self.0 == other.0
+    }
+}
+
+impl Eq for RBT {}
+
+impl RBT {
+    fn new(key: u64) -> Self {
+        Self(Box::into_raw(Box::new(RedBlackTreeNode {
+            key,
+            colour: Colour::Black,
+            left: Self::null(),
+            right: Self::null(),
+            parent: Self::null(),
+        })))
+    }
+
+    unsafe fn deep_clone(&self) -> Self {
+        let mut node = Self::new((*self.0).key);
+        if !self.left().is_null() {
+            node.set_left(self.left().deep_clone());
+            node.left().set_parent(node);
+        }
+        if !self.right().is_null() {
+            node.set_right(self.right().deep_clone());
+            node.right().set_parent(node);
+        }
+        node
+    }
+
+    fn minimum(self) -> Self {
+        let mut temp = self.clone();
+        while !temp.left().is_null() {
+            temp = temp.left();
+        }
+        return temp;
+    }
+
+    fn set_colour(&mut self, colour: Colour) {
+        if !self.is_null() {
+            unsafe { (*self.0).colour = colour; }
+        }
+    }
+
+    fn colour(&self) -> Colour {
+        match self.is_null() {
+            true => Colour::Black,
+            false => unsafe { (*self.0).colour }
+        }
+    }
+
+    fn set_parent(&mut self, parent: Self) {
+        if !self.is_null() {
+            unsafe { (*self.0).parent = parent; }
+        }
+    }
+
+    fn set_right(&mut self, right: Self) {
+        if !self.is_null() {
+            unsafe { (*self.0).right = right; }
+        }
+    }
+
+    fn set_left(&mut self, left: Self) {
+        if !self.is_null() {
+            unsafe { (*self.0).left = left; }
+        }
+    }
+
+    fn parent(&self) -> Self {
+        match self.is_null() {
+            true => Self::null(),
+            false => unsafe { (*self.0).parent.clone() }
+        }
+    }
+
+    fn right(&self) -> Self {
+        match self.is_null() {
+            true => Self::null(),
+            false => unsafe { (*self.0).right.clone() }
+        }
+    }
+
+    fn left(&self) -> Self {
+        match self.is_null() {
+            true => Self::null(),
+            false => unsafe { (*self.0).left.clone() }
+        }
+    }
+
+    fn null() -> Self {
+        Self(ptr::null_mut())
+    }
+
+    fn is_null(&self) -> bool {
+        self.0.is_null()
+    }
+
+    // https://stackoverflow.com/a/66661638
+    fn replace_nth_char_ascii(s: &mut str, idx: usize, newchar: char) {
+        let s_bytes: &mut [u8] = unsafe { s.as_bytes_mut() };
+        assert!(idx < s_bytes.len());
+        assert!(s_bytes[idx].is_ascii());
+        assert!(newchar.is_ascii());
+        // we've made sure this is safe.
+        s_bytes[idx] = newchar as u8;
+    }
+
+    fn _print(&self, f: &mut std::fmt::Formatter<'_>, depth: usize, prefix: char, left_trace: &mut String, right_trace: &mut String) -> std::fmt::Result {
+        if self.is_null() {
+            return Ok(());
+        }
+
+        if !self.left().is_null() {
+            self.left()._print(f, depth + 1, '/', left_trace, right_trace)?;
+        }
+        if prefix == '/' {
+            Self::replace_nth_char_ascii(left_trace, depth - 1, '|');
+        }
+        if prefix == '\\' {
+            Self::replace_nth_char_ascii(right_trace, depth - 1, ' ');
+        }
+        if depth == 0 {
+            write!(f, "-")?;
+        }
+        if depth > 0 {
+            write!(f, " ")?;
+        }
+
+
+        if depth > 0 {
+            for i in 0..(depth - 1) {
+                if left_trace.chars().nth(i).unwrap() == '|' || right_trace.chars().nth(i).unwrap() == '|' {
+                    write!(f, "| ")?;
+                } else {
+                    write!(f, "  ")?;
+                }
+            }
+            write!(f, "{}-", prefix)?;
+        }
+        match self.colour() {
+            Colour::Red => writeln!(f, "({})", unsafe { (*self.0).key })?,
+            Colour::Black => writeln!(f, "[{}]", unsafe { (*self.0).key })?,
+        }
+        Self::replace_nth_char_ascii(left_trace, depth, ' ');
+
+        if !self.right().is_null() {
+            Self::replace_nth_char_ascii(right_trace, depth, '|');
+            self.right()._print(f, depth + 1, '\\', left_trace, right_trace)?;
+        }
+
+        Ok(())
+    }
+}
+
+pub struct RedBlackTree {
+    root: RBT,
+    pub size: usize,
+    print_capacity: usize,
+}
+
+impl Clone for RedBlackTree {
+    fn clone(&self) -> Self {
+        unsafe {
+            let mut ret = RedBlackTree::new(self.print_capacity);
+            ret.root = self.root.deep_clone();
+            ret.size = self.size;
+            ret
+        }
+    }
+}
+
+impl RedBlackTree {
+    pub fn new(print_capacity: usize) -> Self {
+        Self {
+            root: RBT::null(),
+            size: 0,
+            print_capacity,
+        }
+    }
+
+    unsafe fn rotate_left(&mut self, mut node: RBT) {
+        let mut right = node.right();
+        node.set_right(right.left());
+
+        if !right.left().is_null() {
+            right.left().set_parent(node.clone());
+        }
+
+        right.set_parent(node.parent());
+
+        if node == self.root {
+            self.root = right.clone();
+        } else if node == node.parent().left() {
+            node.parent().set_left(right.clone());
+        } else if node == node.parent().right() {
+            node.parent().set_right(right.clone());
+        }
+
+        right.set_left(node.clone());
+        node.set_parent(right.clone());
+    }
+
+    unsafe fn rotate_right(&mut self, mut node: RBT) {
+        let mut left = node.left();
+        node.set_left(left.right());
+
+        if !left.right().is_null() {
+            left.right().set_parent(node.clone());
+        }
+
+        left.set_parent(node.parent());
+
+        if node == self.root {
+            self.root = left.clone();
+        } else if node == node.parent().left() {
+            node.parent().set_left(left.clone());
+        } else if node == node.parent().right() {
+            node.parent().set_right(left.clone());
+        }
+
+        left.set_right(node.clone());
+        node.set_parent(left.clone());
+    }
+
+    unsafe fn insert_fixup(&mut self, mut node: RBT) {
+        use Colour::*;
+
+        let mut parent;
+        let mut grandparent;
+
+        while node.parent().colour() == Red {
+            parent = node.parent();
+            grandparent = parent.parent();
+
+            if parent == grandparent.left() {
+                let mut uncle = grandparent.right();
+                if !uncle.is_null() && uncle.colour() == Red {
+                    uncle.set_colour(Black);
+                    parent.set_colour(Black);
+                    grandparent.set_colour(Red);
+                    node = grandparent;
+                    continue;
+                }
+
+                if parent.right() == node {
+                    self.rotate_left(parent);
+                    let temp = parent;
+                    parent = node;
+                    node = temp;
+                }
+
+                parent.set_colour(Black);
+                grandparent.set_colour(Red);
+                self.rotate_right(grandparent);
+            } else {
+                let mut uncle = grandparent.left();
+                if !uncle.is_null() && uncle.colour() == Red {
+                    uncle.set_colour(Black);
+                    parent.set_colour(Black);
+                    grandparent.set_colour(Black);
+                    node = grandparent;
+                    continue;
+                }
+
+                if parent.left() == node {
+                    self.rotate_right(parent);
+                    let temp = parent;
+                    parent = node;
+                    node = temp;
+                }
+
+                parent.set_colour(Black);
+                grandparent.set_colour(Red);
+                self.rotate_left(grandparent);
+            }
+        }
+        self.root.set_colour(Black);
+    }
+
+    pub fn insert(&mut self, key: u64) {
+        self.size += 1;
+        let mut node = RBT::new(key);
+        let mut y = RBT::null();
+        let mut x = self.root;
+
+        while !x.is_null() {
+            y = x;
+            match node.cmp(&&mut x) {
+                Ordering::Less => {
+                    x = x.left();
+                }
+                _ => {
+                    x = x.right();
+                }
+            };
+        }
+        node.set_parent(y);
+
+        if y.is_null() {
+            self.root = node;
+        } else {
+            match node.cmp(&&mut y) {
+                Ordering::Less => {
+                    y.set_left(node);
+                }
+                _ => {
+                    y.set_right(node);
+                }
+            };
+        }
+
+        node.set_colour(Colour::Red);
+        unsafe { self.insert_fixup(node); }
+    }
+
+    fn find_node(&self, key: u64) -> RBT {
+        if self.root.is_null() {
+            return RBT::null();
+        }
+        let mut temp = &self.root;
+        unsafe {
+            loop {
+                let next = match key.cmp(&(*temp.0).key) {
+                    Ordering::Less => &mut (*temp.0).left,
+                    Ordering::Greater => &mut (*temp.0).right,
+                    Ordering::Equal => return *temp,
+                };
+                if next.is_null() {
+                    break;
+                }
+                temp = next;
+            }
+        }
+
+        RBT::null()
+    }
+
+    unsafe fn delete_fixup(&mut self, mut node: RBT, mut parent: RBT) {
+        use Colour::*;
+
+        let mut other;
+        while node != self.root && node.colour() == Black {
+            if parent.left() == node {
+                other = parent.right();
+
+                if other.colour() == Red {
+                    other.set_colour(Black);
+                    parent.set_colour(Red);
+                    self.rotate_left(parent);
+                    other = parent.right();
+                }
+
+                if other.left().colour() == Black && other.right().colour() == Black {
+                    other.set_colour(Red);
+                    node = parent;
+                    parent = node.parent();
+                } else {
+                    if other.right().colour() == Black {
+                        other.left().set_colour(Black);
+                        other.set_colour(Red);
+                        self.rotate_right(other);
+                        other = parent.right();
+                    }
+
+                    other.set_colour(parent.colour());
+                    parent.set_colour(Black);
+                    other.right().set_colour(Black);
+                    self.rotate_left(parent);
+                    node = self.root;
+                    break;
+                }
+            } else {
+                other = parent.left();
+
+                if other.colour() == Red {
+                    other.set_colour(Black);
+                    parent.set_colour(Red);
+                    self.rotate_right(parent);
+                    other = parent.left();
+                }
+
+                if other.left().colour() == Black && other.right().colour() == Black {
+                    other.set_colour(Red);
+                    node = parent;
+                    parent = node.parent();
+                } else {
+                    if other.left().colour() == Black {
+                        other.right().set_colour(Black);
+                        other.set_colour(Red);
+                        self.rotate_left(other);
+                        other = parent.left();
+                    }
+
+                    other.set_colour(parent.colour());
+                    parent.set_colour(Black);
+                    other.left().set_colour(Black);
+                    self.rotate_right(parent);
+                    node = self.root;
+                    break;
+                }
+            }
+        }
+
+        node.set_colour(Black);
+    }
+
+    unsafe fn delete_node(&mut self, node: RBT) -> u64 {
+        let mut child;
+        let mut parent;
+        let color;
+
+        self.size -= 1;
+
+        if !node.left().is_null() && !node.right().is_null() {
+            let mut replace = node.right().minimum();
+            if node == self.root {
+                self.root = replace;
+            } else {
+                if node.parent().left() == node {
+                    node.parent().set_left(replace);
+                } else {
+                    node.parent().set_right(replace);
+                }
+            }
+
+            child = replace.right();
+            parent = replace.parent();
+            color = replace.colour();
+            if parent == node {
+                parent = replace;
+            } else {
+                if !child.is_null() {
+                    child.set_parent(parent);
+                }
+                parent.set_left(child);
+                replace.set_right(node.right());
+                node.right().set_parent(replace);
+            }
+
+            replace.set_parent(node.parent());
+            replace.set_colour(node.colour());
+            replace.set_left(node.left());
+            node.left().set_parent(replace);
+
+            if color == Colour::Black {
+                self.delete_fixup(child, parent);
+            }
+
+            let obj = Box::from_raw(node.0);
+            return obj.key;
+        }
+
+        if !node.left().is_null() {
+            child = node.left();
+        } else {
+            child = node.right();
+        }
+
+        parent = node.parent();
+        color = node.colour();
+        if !child.is_null() {
+            child.set_parent(parent);
+        }
+
+        if self.root == node {
+            self.root = child
+        } else {
+            if parent.left() == node {
+                parent.set_left(child);
+            } else {
+                parent.set_right(child);
+            }
+        }
+
+        if color == Colour::Black {
+            self.delete_fixup(child, parent);
+        }
+
+        let obj = Box::from_raw(node.0);
+
+        obj.key
+    }
+
+    pub fn delete(&mut self, key: u64) -> bool {
+        let node = self.find_node(key); 
+
+        if node.is_null() {
+            return false;
+        }
+
+        unsafe { self.delete_node(node); }
+
+        true
+    }
+}
+
+impl Display for RedBlackTree {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        self.root._print(f, 0, '-', &mut " ".repeat(self.print_capacity), &mut " ".repeat(self.print_capacity))
+    }
+}