Longest Substring with At Most Two Distinct Characters

You are given a string s. Your task is to determine the length of the longest substring of s that contains at most two distinct characters.

A substring is a contiguous sequence of characters within the string. For example, if s = "eceba", the longest substring with at most two distinct characters is "ece", which has a length of 3.

You can use the sliding window technique to solve this problem. In particular, the size of the window at any point can be described by the formula: \( window\_size = right - left + 1 \), where left and right are the indices marking the beginning and end of the window respectively.

Examples:

• Input: eceba → Output: 3
• Input: ccaabbb → Output: 5

inputFormat

The input consists of a single line containing the string s. The string may be empty and will not contain spaces.

outputFormat

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

eceba

3