def is_prime(n): """判断一个数是否为素数""" if n <= 1: return False if n == 2: return True if n % 2 == 0: return False # 只需检查到sqrt(n)的奇数因子 max_divisor = int(n**0.5) + 1 for i in range(3, max_divisor, 2): if n % i == 0: return False return True def main(): m = int(input()) if is_prime(m): print("prime") else: print("not prime") if __name__ == "__main__": main()