Smallest Balanced Window

Given a string s consisting solely of the characters X and Y, your task is to find the length of the smallest contiguous substring (window) that contains an equal number of X's and Y's. Formally, if we define the net count as \(d(i) = \#X - \#Y\) in the substring, you need to find a window where the net count is 0.

If no such window exists, your program should output -1.

For example, given the string "XXXYXYX", the smallest window that balances the numbers of X and Y is of length 2.

inputFormat

The input consists of a single line containing a non-empty string s which is made up only of the characters X and Y.

Input Format:

s

outputFormat

Output a single integer which represents the length of the smallest substring (window) that has an equal number of X and Y. If no such substring exists, output -1.

Output Format:

result

## sample

XXXYXYX

2