using System;

​

public class Program

{

    public static void Main()

    {

        Console.Write("Enter a positive number: ");

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

        int divider = 2;

        int maxDivider = (int)Math.Sqrt(num);

        bool prime = true;

        while (prime && (divider <= maxDivider))

        {

            if (num % divider == 0)

            {

                prime = false;

            }

​

            divider++;

        }

​

        Console.WriteLine("Prime? " + prime);

    }

}