Longest Unique Substring

Given a string s, your task is to find the longest substring that contains no repeating characters. More formally, for a given string $s$ of length $n$, find a substring $s[i:j]$ where all characters are distinct and the length $j-i$ is maximized. In case there are multiple substrings with the maximum length, return the one that appears first in $s$.

inputFormat

The input is given via stdin as a single line containing the string s. The string may include any printable ASCII characters. It is possible that the string is empty.

outputFormat

Output via stdout the longest substring of s that does not contain any repeating characters. If multiple answers exist, output the first one encountered.