First Unique Character

Given a string s consisting of only lowercase English letters, find the index of the first non-repeating character in s. If no such character exists, output \(-1\).

For example, if s = "leetcode", the answer is 0, because 'l' is the first unique character. In contrast, for s = "aabb", all characters repeat, so the answer is -1.

Note: The string input may be empty. When working with inputs, read a single line from standard input and output the result to standard output.

inputFormat

The input consists of a single line containing the string s with only lowercase English letters. The string may be empty.

outputFormat

Output a single integer representing the index of the first non-repeating character in s. If no such character exists, output -1.

leetcode

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