Longest Substring with Even Occurrences

Find the longest contiguous substring in which every English letter occurs an even number of times; if no non-empty substring exists, output 0.

This site's standard input/output format and any supplementary ranges follow this problem's description.

输入格式

One line containing a string of only lowercase English letters, 1≤|S|≤100000.

输出格式

Output the longest length.

样例 1

输入：

bdaaadadb

输出：

6

样例 2

输入：

abacb

输出：

0

样例 3

输入：

zthtzh

输出：

6