Given a number n, find the smallest number that has same set of digits as n and is greater than n. If n is the greatest possible number with its set of digits, report it.

Example 1:

Input:
N = 143
Output: 314
Explanation: Numbers possible with digits 
1, 3 and 4 are: 134, 143, 314, 341, 413, 431.
The first greater number after 143 is 314.

​Example 2:

Input: 
N = 431
Output: not possible
Explanation: Numbers possible with digits
1, 3 and 4 are: 134, 143, 314, 341, 413, 431.
Clearly, there's no number greater than 431.

Your Task:
You don't need to read input or print anything. Your task is to complete the function findNext () which takes an integer N as input and returns the smallest number greater than N with the same set of digits as N. If such a number is not possible, return -1.

Expected Time Complexity: O(LogN).
Expected Auxiliary Space: O(LogN).

Constraints:
1 ≤ N ≤ 100000