Longest Substring Without Repeating Characters

Given a string s, your task is to find the length of the longest substring that contains no repeating characters.

For a string s with length n, we define the length of a substring starting at index i and ending at index j-1 (for 0 ≤ i < j ≤ n) as j - i. We require that all characters in s[i...j-1] are unique. In mathematical notation, the answer is given by:

[ L = \max_{0 \leq i \leq j \leq n ; \text{and} ; s[i...j-1], \text{has all unique characters}} (j - i) ]

You need to implement an efficient solution that works well for large inputs.

inputFormat

The input consists of a single line containing a string s. The string may be empty and may contain any visible characters.

outputFormat

Output a single integer, which is the length of the longest substring of s that does not contain any repeating characters.

abcabcbb

3