class Solution:
    def titleToNumber(self, columnTitle: str) -> int:
        res=0
        length = len(columnTitle)
        for i in range(length):
            res+=pow(26,length-i-1)*(ord(columnTitle[i])-64)
        return res

int titleToNumber(char * columnTitle){
    int res=0;
    int length = strlen(columnTitle);
    for(int i=0;i<length;i++)
        res+=pow(26,length-i-1)*(columnTitle[i]-64);
    return res;
}