Longest Substring with At Most Two Distinct Characters

Given a string s, your task is to find the length of the longest substring that contains at most two distinct characters.

For example:

• For s = "eceba", the longest valid substring is "ece" which has a length of 3.
• For s = "ccaabbb", the longest valid substring is "aabbb" which has a length of 5.

You are required to read the input from stdin and write the result to stdout.

Note: The input string can be empty. In that case, the output should be 0.

inputFormat

The input consists of a single line containing the string s. The string may be empty and will contain only ASCII characters.

outputFormat

Output a single integer representing the length of the longest substring of s that contains at most two distinct characters.## sample

0