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. A substring is a contiguous portion of the string.

For example, given s = "eceba", the longest substring that contains at most two distinct characters is "ece", which has a length of 3.

It is guaranteed that s consists of only English letters.

inputFormat

The input consists of a single line containing the string s.

outputFormat

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

abcbbbbcccbdddadacb

10