using System;

class PositiveInteger
{
    static void Main()
    {
        int a = 81;
        for (int n = 2; n < a; n++)
        {
            if (a % n == 0)
            {
            Console.WriteLine("This number is not prime.");
            return;
            Console.WriteLine("This number is prime");
            }
        }
    }
}