using System;

​

public class Program

{

    public static void Main()

    {

        int num = 4;

        int count1 = 1;

        int count2 = 1;

        while (count1 <= num) 

        {

            count2 = 1;

            while (count2 <= count1)

            {

                Console.Write(count1);

                count2++;

            }

​

            Console.WriteLine();

            count1++;

        }

    }

}