PROGRAMMING:Number of black holes
The number of black holes, also known as the trap number, also known as "kaprekar problem", is a kind of number with peculiar transformation characteristics.
Any three digit number with different digits will always get 495 after a limited number of "rearrangement and subtraction" operations. The final 495 is the number of three black holes. The so-called "rearrangement subtraction" operation means that the maximum number of rearranged digits minus the minimum number of rearranged digits（ 6174 is the number of four black holes.)
For example, for three digit 207:
-In the first rearrangement, 720 - 27 = 693;
-In the second rearrangement, 963 - 369 = 594;
-In the third rearrangement, 954 - 459 = 495;
It will stay at 495 in the future. If all three digits of three digits are the same, it will be 0 after one conversion.
Arbitrary input of a three digit, programming gives the process of rearrangement and subtraction.
###Input format:
Input gives a three digit number on a line.
###Output format:
Output the rearrangement subtraction process in the following format:
```
Serial number: maximum number after number rearrangement - minimum number after number rearrangement = difference
```
The sequence number starts from 1 until 495 appears to the right of the equal sign.
###Input example:
```in
one hundred and twenty-three
```
###Output example:
```out
1: 321 - 123 = 198
2: 981 - 189 = 792
3: 972 - 279 = 693
4: 963 - 369 = 594
5: 954 - 459 = 495
```
answer：If there is no answer, please comment
Any three digit number with different digits will always get 495 after a limited number of "rearrangement and subtraction" operations. The final 495 is the number of three black holes. The so-called "rearrangement subtraction" operation means that the maximum number of rearranged digits minus the minimum number of rearranged digits（ 6174 is the number of four black holes.)
For example, for three digit 207:
-In the first rearrangement, 720 - 27 = 693;
-In the second rearrangement, 963 - 369 = 594;
-In the third rearrangement, 954 - 459 = 495;
It will stay at 495 in the future. If all three digits of three digits are the same, it will be 0 after one conversion.
Arbitrary input of a three digit, programming gives the process of rearrangement and subtraction.
###Input format:
Input gives a three digit number on a line.
###Output format:
Output the rearrangement subtraction process in the following format:
```
Serial number: maximum number after number rearrangement - minimum number after number rearrangement = difference
```
The sequence number starts from 1 until 495 appears to the right of the equal sign.
###Input example:
```in
one hundred and twenty-three
```
###Output example:
```out
1: 321 - 123 = 198
2: 981 - 189 = 792
3: 972 - 279 = 693
4: 963 - 369 = 594
5: 954 - 459 = 495
```
answer：If there is no answer, please comment