diff --git a/zad5/.ccls b/zad5/.ccls
new file mode 100644
index 0000000..9f91bd0
--- /dev/null
+++ b/zad5/.ccls
@@ -0,0 +1,21 @@
+gcc
+%c -std=c99
+%h
+-Iinclude
+-Wall
+-Wextra
+-Wpedantic
+-Wstrict-aliasing
+-Wfloat-equal
+-Wundef
+-Wshadow
+-Wpointer-arith
+-Wcast-align
+-Wstrict-prototypes
+-Wstrict-overflow=5
+-Wwrite-strings
+-Wcast-qual
+-Wswitch-default
+-Wswitch-enum
+-Wconversion
+-Wunreachable-code
diff --git a/zad5/include/mod.h b/zad5/include/mod.h
new file mode 100644
index 0000000..4a827dc
--- /dev/null
+++ b/zad5/include/mod.h
@@ -0,0 +1,19 @@
+#ifndef _JPP_L1_Z5_MOD_H
+#define _JPP_L1_Z5_MOD_H
+
+#include <stdbool.h>
+#include <stdint.h>
+
+unsigned int factorial(unsigned int n);
+
+unsigned int gcd(unsigned int a, unsigned int b);
+
+typedef struct {
+    bool resultExists;
+    int n;
+    int m;
+} Result;
+
+Result diophantine(int a, int b, int c);
+
+#endif // _JPP_L1_Z5_MOD_H
diff --git a/zad5/iter/mod.c b/zad5/iter/mod.c
new file mode 100644
index 0000000..79e367b
--- /dev/null
+++ b/zad5/iter/mod.c
@@ -0,0 +1,82 @@
+#include "../include/mod.h"
+
+#include <stddef.h>
+#include <stdlib.h>
+
+unsigned int factorial(unsigned int n) {
+    unsigned int result = 1;
+
+    for (size_t i = 1; i <= n; ++i) {
+        result *= i;
+    }
+
+    return result;
+}
+
+unsigned int gcd(unsigned int a, unsigned int b) {
+    if (a == 0) return b;
+
+    size_t r;
+
+    while (b > 0) {
+        r = a % b;
+
+        a = b;
+        b = r;
+    }
+
+    return a;
+}
+
+inline int extended_gcd(int a, int b, int *x, int *y) {
+    *x = 1;
+    *y = 0;
+    int x1 = 0;
+    int y1 = 1;
+    int q;
+    int temp_x, temp_y, temp_b;
+    while (b != 0) {
+        q = a / b;
+
+        temp_x = *x - q * x1;
+        temp_y = *y - q * y1;
+        *x = x1;
+        *y = y1;
+        x1 = temp_x;
+        y1 = temp_y;
+
+        temp_b = a - q * b;
+        a = b;
+        b = temp_b;
+    }
+
+    return a;
+}
+
+Result diophantine(int a, int b, int c) {
+    Result r = {
+        .resultExists = false,
+        .n = 0,
+        .m = 0,
+    };
+
+    if (a == 0 && b == 0)
+        return r;
+    int x0 = 0;
+    int y0 = 0;
+    int g = extended_gcd(abs(a), abs(b), &x0, &y0);
+
+    if (c % g)
+        return r;
+
+    x0 *= c / g;
+    y0 *= c / g;
+    if (a < 0) x0 = -x0;
+    if (b < 0) y0 = -y0;
+
+    r.resultExists = true;
+    r.n = x0;
+    r.m = y0;
+
+    return r;
+}
diff --git a/zad5/rec/mod.c b/zad5/rec/mod.c
new file mode 100644
index 0000000..7fe5bdd
--- /dev/null
+++ b/zad5/rec/mod.c
@@ -0,0 +1,63 @@
+#include "../include/mod.h"
+
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+
+unsigned int factorial(unsigned int n) {
+    if (n == 0 || n == 1) {
+        return 1;
+    }
+
+    return n * factorial(n - 1);
+}
+
+unsigned int gcd(unsigned int a, unsigned int b) {
+    if (b == 0) {
+        return a;
+    }
+
+    return gcd(b, a % b);
+}
+
+inline int extended_gcd(int a, int b, int *x, int *y) {
+    if (b == 0) {
+        *x = 1;
+        *y = 0;
+        return a;
+    }
+    int x1, y1;
+    int d = extended_gcd(b, a % b, &x1, &y1);
+    *x = y1;
+    *y = x1 - y1 * (a / b);
+    return d;
+}
+
+Result diophantine(int a, int b, int c) {
+    Result r = {
+        .resultExists = false,
+        .n = 0,
+        .m = 0,
+    };
+
+    if (a == 0 && b == 0)
+        return r;
+    int x0 = 0;
+    int y0 = 0;
+    int g = extended_gcd(abs(a), abs(b), &x0, &y0);
+
+    if (c % g)
+        return r;
+
+    x0 *= c / g;
+    y0 *= c / g;
+    if (a < 0) x0 = -x0;
+    if (b < 0) y0 = -y0;
+
+    r.resultExists = true;
+    r.n = x0;
+    r.m = y0;
+
+    return r;
+}
diff --git a/zad5/src/main.adb b/zad5/src/main.adb
new file mode 100644
index 0000000..f845744
--- /dev/null
+++ b/zad5/src/main.adb
@@ -0,0 +1,48 @@
+with Ada.Text_IO; use Ada.Text_IO;
+with Ada.Strings; use Ada.Strings;
+with Ada.Strings.Unbounded; use Ada.Strings.Unbounded;
+with Interfaces.C; use Interfaces.C;
+
+procedure Main is
+
+    function gcd(a : Natural; b : Natural) return Natural
+    with
+        Import        => True,
+        Convention    => C,
+        External_Name => "gcd";
+
+    function factorial(n : Natural) return Natural
+    with
+        Import        => True,
+        Convention    => C,
+        External_Name => "factorial";
+
+    type Result is record
+        resultExists : Boolean;
+        n : Integer;
+        m : Integer;
+    end record
+    with Convention => C;
+
+    function diophantine(a : Integer; b : Integer; c : Integer) return Result
+    with
+        Import        => True,
+        Convention    => C,
+        External_Name => "diophantine";
+
+    gcdResult : Natural;
+    factorialResult : Natural;
+    diophantineResult : Result;
+begin
+    gcdResult := gcd(10, 5);
+    factorialResult := factorial(5);
+    diophantineResult := diophantine(1027, 712, 1);
+
+    Put_Line("gcd(a, b):" & Natural'Image(gcdResult));
+    Put_Line("factorial(a):" & Natural'Image(factorialResult));
+    if not diophantineResult.resultExists then
+        Put_Line("dupa");
+    else 
+        Put_Line("diophantine(a, b, c): " & Integer'Image(diophantineResult.n) & "," & Integer'Image(diophantineResult.m));
+    end if;
+end Main;
diff --git a/zad5/zad5.gpr b/zad5/zad5.gpr
new file mode 100644
index 0000000..35a6258
--- /dev/null
+++ b/zad5/zad5.gpr
@@ -0,0 +1,11 @@
+project Zad5 is
+    type Impl_Type is ("iter", "rec");
+    Impl : Impl_Type := external ("impl", "iter");
+
+    for Languages use ("ada", "c");
+    
+    for Main use ("main.adb");
+    for Source_Dirs use ("src", Impl);
+    for Object_Dir use "target";
+
+end Zad5;