diff --git a/week01/1-Warmup-Problems/good_solutions.rb b/week01/1-Warmup-Problems/good_solutions.rb
index c3c1f0a..ca82d19 100644
--- a/week01/1-Warmup-Problems/good_solutions.rb
+++ b/week01/1-Warmup-Problems/good_solutions.rb
@@ -113,11 +113,24 @@ def largest_palindrome(n)
 end
 
 def prime?(n)
-  # Waiting for PR
+  num = n.to_i.abs
+
+  return false if num == 0 || num == 1  
+  2.upto(num - 1) do |i|
+    return false if num % i == 0
+  end
+
+  true
 end
 
-def list_first_primes(n)
-  # Waiting for PR
+def Integer.all
+  Enumerator.new do |yielder, n: 0|
+    loop { yielder.yield(n += 1) }
+  end.lazy
+end
+
+def first_primes(n)
+  Integer.all.select { |num| prime?(num) && num > 1 }.first(n)
 end
 
 def sieve(n)