using System;

public static class Program

{

    public static void Main()

    {   Console.WriteLine("Enter string");

        string x = Console.ReadLine();

     Console.WriteLine("Enter Random Append size");

     int intValue;

    string z = Console.ReadLine();

    if(Int32.TryParse(z, out intValue))

    Console.WriteLine("Correct number typed");

    else

    Console.WriteLine("The input is not a valid integer");

        //int z = Console.ReadLine();

        Console.WriteLine(x.ExtensionAppendNo(intValue));

    }

    public static string ExtensionAppendNo(this string y, int w )

    { string r=null;

        for (int i=0;i<w;i++)

        {

         string random = new Random().Next(0,10).ToString();

            r=r+random;

            random=null;

        }

    return y+r;

    }

​

}

​