First Unique Character in a String

Given a string s, find the index of the first non-repeating character.

Return the index of that character. If every character appears more than once, return -1.

Example 1

Input

s = "leetcode"

Output

0

Explanation

'l' appears only once in the string and is the first unique character.

Example 2

Input

s = "loveleetcode"

Output

2

Explanation

'v' is the first character that appears exactly once.

Explanation

Every character appears more than once, so there is no unique character.

Constraints

• 1 <= s.length <= 10^5

• s contains only lowercase English letters