class Solution {
    public int titleToNumber(String s) {
        char[] chas = s.toCharArray();
        int res=0;
        int temp=1;
        for(int i=chas.length-1;i>-1;i--)
        {
            int cur=chas[i]-'A'+1;
            res+=cur*temp;
            temp*=26;
        }
        return res;
    }
}