First Unique Character

Given a string s, find the first non-repeating character and return its index. Return -1 if none exists. Count character frequencies, then find first with count 1. Example: 'leetcode' → 0 (l appears once, is first)

Entrada

A single line containing a string.

Salida

The index (0-based) or -1.

Ejemplo

leetcode

Esperado

0