Unique Characters Checker

You are given a string consisting only of lowercase alphabetic characters. Your task is to determine whether all the characters in the string are unique. In other words, check if no character appears more than once in the string.

The answer should be printed as True if all characters are unique, or False otherwise.

Note: An empty string is considered to have all unique characters.

Mathematical formulation: Let \( S \) be a string of length \( n \). Define a function \( f: S \to \{0,1\} \) where \( f(c) = 1 \) if character \( c \) appears exactly once in \( S \) and 0 otherwise. The string has all unique characters if and only if \( \sum_{c \in S} f(c) = n \).

inputFormat

The input consists of a single line containing a string \( s \) (where \( s \) only contains lowercase letters).

outputFormat

Output a single line: True if all characters in the string are unique, or False otherwise.

algorithm

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