First Non-Repeating Character

Given a string s, find the first character that does not repeat. If every character in the string appears more than once, print an asterisk (*).

The task is to iterate through the string and identify the very first character that occurs exactly once. Use efficient methods for counting character occurrences if possible.

Note: The input string may contain both uppercase and lowercase English letters. The case is significant, i.e., 'a' is considered different from 'A'.

In mathematical notation, let \(s = s_1s_2\dots s_n\), find the smallest index \(i\) such that \(\#(s_i) = 1\). If no such \(i\) exists, output \('*'\).

inputFormat

The input is read from standard input (stdin) and consists of a single line containing the string s.

outputFormat

Print a single character to standard output (stdout): the first non-repeating character of the string. If all characters repeat, print *.

aabbcc

*