using System;
using System.Linq;
public class Program
{
public static void Main()
string num = "6175";
int count = num.Length;
Console.WriteLine(num);
while(num != "6174"){
var min = String.Concat(num.OrderBy(c=>c));
var max = String.Concat(num.OrderByDescending(c=>c));
num = Convert.ToString(Convert.ToInt32(max)- Convert.ToInt32(min));
if(num.Length < count)
num = "0"+num;
}