Write a function solution that, given an integer N, return the maximum possible value obtained by inserting '5' digit inside the decimal representation of integer N. Example:
- Given N = 268 function return 5268
- Given N = 670 function return 6750
- Given N = 0 function return 50
- Given N = -999 function return -5999
Assume that;
- N is an integer within the range [-8000, 8000].