Unique Characters Check

Given a string \(s\), check whether all characters in the string are unique. That is, determine if no character appears more than once.

If all characters are unique, output YES. Otherwise, output NO.

Formally, for a given string \(s\), if \(|s| = |\{ s \}|\), then output \(YES\), otherwise output \(NO\).

inputFormat

The input is a single string (s) provided via standard input. The string may be empty and consists of ASCII characters.

outputFormat

Output a single line containing either (YES) or (NO), according to whether all characters in the input string are unique.## sample

abcdef

YES