using System;

public class Program

{

    public static void Main()

    {

        int cislo = 0;

        while (cislo < 3)

        {

            Console.WriteLine("Ahoj");

            cislo = cislo + 1;

        }

        for (int i = 0; i < 3; i = i + 1)

        {

            Console.WriteLine("Ahoj");

        }

        int cifra = 5;

        while (cifra > 0)

        {

            Console.WriteLine(cifra);

            cifra = cifra - 1;

        }

        int nummer = 0;

        while (nummer < 21)

        {

            Console.WriteLine(nummer);

            nummer = nummer + 2;

        }

        int x = 0;

        while (x < 11)

        {

            Console.WriteLine(x * 2);

            x = x + 1;

        }

    }

}