Goal
A growing number is a number where each digit, from left to right, is greater than or equal to the previous one.
Given a number n, which may or may not be a growing number, you have to find the first growing number > n.
Example:
With n = 19, the first growing number greater than n is 22, because both 20 and 21 have a second digit that is smaller than the first one.
Note: This problem can be solved without converting n to a number.
Input
line 1: a string representing the number n
Output
line 1: the first growing number > n
