using System;

public class Program

{

    public static void Main()

    {

        //Chritopher Martinez Sanchez

        int num;

        Console.WriteLine("Write a number and I will tell you if it is prime or not. ");

        num = int.Parse(Console.ReadLine());

        for ( int i = 1; i <= 20; i++)

        {

        if (1 <= 20)

            {

             num++; 

       }

  }     

  if ( num == 20)

  {

        Console.WriteLine("The number is prime.");

  }

  else 

  {

        Console.WriteLine("The number is not prime.");

      }

    }

}