题目描述

For any 4-digit integer except the ones with all the digits being the
same, if we sort the digits in non-increasing order 

 first, and then in non-decreasing order, a new number can be obtained
by taking the second number from the first 

 one. Repeat in this manner we will soon end up at the number 6174 --
the "black hole" of 4-digit numbers. This 

 number is named Kaprekar Constant.



 For example, start from 6767, we'll get:



 7766 - 6677 = 1089

 9810 - 0189 = 9621

 9621 - 1269 = 8352

 8532 - 2358 = 6174

 7641 - 1467 = 6174

 ... ...



 Given any 4-digit number, you are supposed to illustrate the way it
gets into the black hole.

输入描述:

Each input file contains one test case which gives a positive integer N in the range (0, 10000).

输出描述:

If all the 4 digits of N are the same, print in one line the equation "N - N = 0000". Else print each step of calculation in a line until 6174 
comes out as the difference. All the numbers must be printed as 4-digit numbers.

输入例子:

6767

输出例子:

7766 - 6677 = 1089
9810 - 0189 = 9621
9621 - 1269 = 8352
8532 - 2358 = 6174