#author("2026-04-23T00:19:48+09:00","default:vip","vip") #author("2026-04-23T00:28:46+09:00","default:vip","vip") using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; namespace SosuHantei { internal class Program { static void Main(string[] args) { var input = int.Parse(Console.ReadLine()); var ans = SosuHantei(input); Console.WriteLine(ans ? "素数" : "素数ではない"); } /// <summary> /// 素数かどうかを検証します /// </summary> /// <param name="n"></param> static bool SosuHantei(int n) { if(n <= 1) { return false; } for (var i = 2; i <= n - 1; i++) for (var i = 2; i * i <= n; i++) { if (n % i == 0) { return false; } } return true; } } }