using System;

public class Program

{

    public static void Main()

    {

        int x;

        x=0;

        while(x<20){

        x=x+1;

        Console.WriteLine(x);

        }

    }

}

​

​

​

​

​

        //do{

        //x=x+1;

        //Console.WriteLine(x);

        //}while(x<20);