// Given a string, find the first non-repeating character in it and return it's index. If it doesn't exist, return -1.

// Examples:

// s = "leetcode"
// return 0.

// s = "loveleetcode",
// return 2.
// Note: You may assume the string contain only lowercase letters.

// Given a string, find the first non-repeating character in it and return it's index. If it doesn't exist, return -1.

// Examples:

// s = "leetcode"
// return 0.

// s = "loveleetcode",
// return 2.
// Note: You may assume the string contain only lowercase letters.

/**
 * @param {string} s
 * @return {number}
 */



add params