First Non-Repeating Character After Filtering

Given a string, your task is to filter out all non-alphabetical characters and then determine the first character in the filtered string which does not repeat. If every character appears more than once after filtering, output "None".

For example, given the input hello#world, after filtering the string becomes helloworld and the first non-repeating character is h.

Remember that the input is provided via standard input (stdin) and your answer should be printed to standard output (stdout).

inputFormat

The input consists of a single line containing a string, which may include special characters. Characters that are not alphabetical (i.e., not in [a-zA-Z]) should be ignored in processing.

outputFormat

Output a single string: the first non-repeating alphabetical character from the filtered string. If every character repeats, output "None".## sample

hello#world

h