LOOP_COUNT = 1_000_000 EXPECTED_CHECKSUM = 5_000_001 def math_loop(limit: int) -> int: i = 0 acc = 1 while i < limit: acc = acc + ((i + 3) * 2) acc = acc - 1_000_000_000 if acc > 1_000_000_000 else acc i += 1 return acc def configured_loop_count() -> int: try: value = int(input().strip()) except (EOFError, ValueError): return LOOP_COUNT return value if value > 0 else LOOP_COUNT def main() -> int: result = math_loop(configured_loop_count()) print(result) return 0 if result == EXPECTED_CHECKSUM else 1 if __name__ == "__main__": raise SystemExit(main())