public class Solution {    public int FirstUniqChar(string s) {        var arr = new int[26];    	var len = s.Length;    	for (var i = 0;i < len; i++){    		arr[s[i]-97]++;    	}    	    	for (var i = 0;i < len; i++){    		if(arr[s[i]-97] == 1){    			return i;    		}    	}    	    	return -1;    }}