using System;

public class Program

{

    public static void Main()

    {

        int i = 0; 

        int j;

        do

        {

            j = 1;

            i++;

            do

            {

            Console.Write(i);

            j++;    

            }while(j <= i);

                Console.WriteLine("");

        }while(i <=3);

        Console.WriteLine("");

​

​

}

}