Fixing bug

utils.py

@@ -21,9 +21,15 @@ def execute_code(code: str, stdin: str = "") -> tuple:
     """
     with capture_output() as (stdout, stderr):
         try:
-            # Simulate stdin by overriding input() calls
-            local_vars = {"input": lambda: stdin.splitlines().pop(0) if stdin.strip() else ""}
+            # Create a generator for stdin lines
+            inputs = iter(stdin.splitlines())
+
+            # Proper lambda that accepts optional prompt
+            input_override = lambda prompt='': next(inputs, '')
+
+            local_vars = {"input": input_override}
             exec(code, {}, local_vars)
+
             return stdout.getvalue().strip(), stderr.getvalue().strip(), None
         except Exception as e:
             return stdout.getvalue().strip(), stderr.getvalue().strip(), str(e)