diff --git a/l4/z1/rsa-rs/src/main.rs b/l4/z1/rsa-rs/src/main.rs
index f92d263..54d61d9 100644
--- a/l4/z1/rsa-rs/src/main.rs
+++ b/l4/z1/rsa-rs/src/main.rs
@@ -1,6 +1,9 @@
+use std::str::FromStr;
+
 use rand::thread_rng;
 use num_bigint::{BigInt, BigUint, RandBigInt, ToBigInt};
 use num_traits::{One, Zero};
+use num_prime::nt_funcs::is_prime;
 
 #[derive(Clone, Debug, PartialEq)]
 struct Key {
@@ -14,17 +17,6 @@ struct KeyPair {
     public: Key,
 }
 
-fn is_prime(n: &BigUint) -> bool {
-    let mut i = BigUint::from(2u32);
-    while &i < &n.sqrt() {
-        if n % &i == 0u32.into() {
-            return false;
-        }
-        i += 1u32;
-    }
-    true
-}
-
 fn euclid(a: &BigUint, b: &BigUint) -> BigUint {
     let mut s0 = BigInt::one();
     let mut s1 = BigInt::zero();
@@ -68,7 +60,7 @@ fn find_e(phi: &BigUint) -> BigUint {
 }
 
 fn generate_key_pair(p: &BigUint, q: &BigUint) -> Option<KeyPair> {
-    if !is_prime(p) || !is_prime(q) || p == q {
+    if !is_prime(p, None).probably() || !is_prime(q, None).probably() || p == q {
         return None;
     }
 
@@ -120,7 +112,6 @@ fn find_private_key(n: &BigUint, e: &BigUint, d: &BigUint) -> (BigUint, BigUint)
     let kphi = d * e - 1u32;
     let mut t = kphi.clone();
     while &t % 2u32 == BigUint::zero() {
-        // println!("t: {t}");
         t /= 2u32;
     }
     
@@ -130,16 +121,12 @@ fn find_private_key(n: &BigUint, e: &BigUint, d: &BigUint) -> (BigUint, BigUint)
     while a < 100u32.into() {
         let mut k = t.clone();
         while k < kphi {
-            // println!("a: {a}, kphi: {kphi}, k: {k}, n: {n}");
             let x = pow_mod(&a, &k, n);
-            // println!("x: {x}; n: {n}");
             if x != BigUint::one() &&
                 x != (n - 1u32) &&
                 pow_mod(&x, &2u32.into(), n) == BigUint::one()
             {
-                // println!("x: {x}; n: {n}");
                 p = gcd(&(x - BigUint::one()), n);
-                // println!("p: {p}");
                 break;
             }
             k *= 2u32;
@@ -153,8 +140,12 @@ fn find_private_key(n: &BigUint, e: &BigUint, d: &BigUint) -> (BigUint, BigUint)
 }
 
 fn main() {
-    let p1 = BigUint::from(1234577u32);
-    let p2 = BigUint::from(1234567891u32);
+    let p1 = BigUint::from_str(
+        "4749005082931655265795279207137334688882888522100146336507022668451002460179375611672565276762330501"
+    ).unwrap();
+    let p2 = BigUint::from_str(
+        "9310861498193275957242744132472955539605730477090317642199650992920633866919589011169367627123252973"
+    ).unwrap();
 
     let pair_a = generate_key_pair(&p1, &p2)
         .expect("failed to generate key pair a");