using System;

public class Program

{

    public static void Main()

    {

        int m;

        Console.WriteLine("give me a number higher than 20");

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

        while (m >= 20)

        {

        Console.WriteLine("give me a numbrr higher than 20");

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

        } 

    }

}