Shortest Sequential Palindromic Substring

You are given a string s. A sequential palindromic substring is defined as a contiguous substring that contains at least one pair of identical consecutive characters. Since the smallest possible substring that meets this requirement is of length 2 (i.e. the pair of identical letters), your task is to determine if such a substring exists in s. If it exists, output 2; otherwise, output -1.

Examples:

• For s = "abbce", the output is 2 because the substring "bb" exists.
• For s = "abcdef", there is no sequential palindromic substring, so the output is -1.
• For s = "abcddcba", even though the string is a palindrome as a whole, the shortest sequential palindromic substring is "dd" and the output is 2.

The solution must read the input from stdin and print the answer to stdout.

inputFormat

The input consists of a single line containing a non-empty string s made up of lowercase English letters.

Note: The input is provided via standard input (stdin).

outputFormat

Output a single integer: 2 if a sequential palindromic substring exists in s (i.e. at least one pair of consecutive identical letters is found), or -1 otherwise. The result should be printed via standard output (stdout).

## sample

abbce

2

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