using System;

​

public class Program

{

    public static void Main()

    {

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

        int number = Int32.Parse(Console.ReadLine());

        int divider = 2;

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

        string primeNumber = "Yes";

        while (primeNumber == "Yes" && (divider <= maxDivider))

        {

            if (number % divider == 0)

                primeNumber = "No";

            divider++;

        }

​

        Console.WriteLine($"Is {number} prime number? {primeNumber}");

    }

}