Longest Palindromic String Length

Given a string s, determine the length of the longest palindromic string that can be formed by rearranging its characters, with the possibility of removing one character. In other words, you are allowed to use each character in s, and if there are characters that appear an odd number of times, you may reduce one occurrence in one of these groups so that it can be paired, and optionally add one extra character in the center of the palindrome. The problem can be mathematically formulated as follows:

Given the frequency ( f(c) ) for each character ( c ) in the string, the maximum palindrome length is [ \text{length} = \sum_{c} \Bigl( f(c) - (f(c) \bmod 2) \Bigr) + \mathbf{1}_{{\exists c: f(c) \bmod 2 =1}}, ]

where ( \mathbf{1}_{{\exists c: f(c) \bmod 2 =1}} ) is 1 if there is at least one character with an odd frequency, and 0 otherwise.

Note: Input will be provided via standard input (stdin) as a single line and the result should be printed to standard output (stdout).

inputFormat

The input consists of a single line containing a non-empty string s composed of ASCII characters. The string may be empty as well.

outputFormat

Output a single integer representing the length of the longest palindromic string that can be formed from the input string.## sample

abccccdd

7