Prime 3

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace _06_PrimeChecker
{
    class Program
    {
        static void Main(string[] args)
        {
            long n = long.Parse(Console.ReadLine());
            Console.WriteLine(IsPrime(n));
        }

        private static bool IsPrime(long n)
        {
            if (n == 2)
            {
                return true;
            }
            if (n % 2 == 0 || n == 1)
            {
                return false;
            }
            for (int i = 3; i <= (long)Math.Sqrt(n); i+=2)
            {
                if (n % i == 0)
                {
                    return false;
                }
            }
            return true;
        }

    }
}