First Unique Character Finder

Given a string \(S\) consisting of lowercase English letters, your task is to find the first unique character in the string. A unique character is defined as a character that appears exactly once in \(S\). If there is no such character, output an empty string.

For example, if \(S = \texttt{swiss}\), the first unique character is \(\texttt{w}\). Similarly, if \(S = \texttt{aabbcc}\), there is no unique character, and you should output an empty string.

inputFormat

The input consists of a single line that contains the string \(S\) comprised only of lowercase English letters.

outputFormat

Output the first unique character of the string. If no unique character exists, print an empty string.

swiss

w