Problem Statement

We have a string $s$ consisting of lowercase English letters. Snuke can perform the following operation repeatedly:

• Insert a letter x to any position in $s$ of his choice, including the beginning and end of $s$.

Snuke's objective is to turn $s$ into a palindrome. Determine whether the objective is achievable. If it is achievable, find the minimum number of operations required.

Notes

A palindrome is a string that reads the same forward and backward. For example, a, aa, abba and abcba are palindromes, while ab, abab and abcda are not.

Constraints

• $1 \\leq |s| \\leq 10^5$
• $s$ consists of lowercase English letters.

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Input

Input is given from Standard Input in the following format:

$s$

Output

If the objective is achievable, print the number of operations required. If it is not, print -1 instead.

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Sample Input 1

xabxa

Sample Output 1

2

One solution is as follows (newly inserted x are shown in bold):

xabxa → xaxbxa → xaxbxax

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Sample Input 2

ab

Sample Output 2

-1

No sequence of operations can turn $s$ into a palindrome.

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Sample Input 3

a

Sample Output 3

0

$s$ is a palindrome already at the beginning.

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Sample Input 4

oxxx

Sample Output 4

3

One solution is as follows:

oxxx → xoxxx → xxoxxx → xxxoxxx