public class Solution {

    private int ConvertToC(char c)

        {

            int rnt = ;

            switch (c)

            {

                case 'A':

                case 'a':

                    rnt = ;

                    break;

                case 'B':

                case 'b':

                    rnt = ;

                    break;

                case 'C':

                case 'c':

                    rnt = ;

                    break;

                case 'D':

                case 'd':

                    rnt = ;

                    break;

                case 'E':

                case 'e':

                    rnt = ;

                    break;

                case 'F':

                case 'f':

                    rnt = ;

                    break;

                case 'G':

                case 'g':

                    rnt = ;

                    break;

                case 'H':

                case 'h':

                    rnt = ;

                    break;

                case 'I':

                case 'i':

                    rnt = ;

                    break;

                case 'J':

                case 'j':

                    rnt = ;

                    break;

                case 'K':

                case 'k':

                    rnt = ;

                    break;

                case 'L':

                case 'l':

                    rnt = ;

                    break;

                case 'M':

                case 'm':

                    rnt = ;

                    break;

                case 'N':

                case 'n':

                    rnt = ;

                    break;

                case 'O':

                case 'o':

                    rnt = ;

                    break;

                case 'P':

                case 'p':

                    rnt = ;

                    break;

                case 'Q':

                case 'q':

                    rnt = ;

                    break;

                case 'R':

                case 'r':

                    rnt = ;

                    break;

                case 'S':

                case 's':

                    rnt = ;

                    break;

                case 'T':

                case 't':

                    rnt = ;

                    break;

                case 'U':

                case 'u':

                    rnt = ;

                    break;

                case 'V':

                case 'v':

                    rnt = ;

                    break;

                case 'W':

                case 'w':

                    rnt = ;

                    break;

                case 'X':

                case 'x':

                    rnt = ;

                    break;

                case 'Y':

                case 'y':

                    rnt = ;

                    break;

                case 'Z':

                case 'z':

                    rnt = ;

                    break;

                default:

                    rnt = ;

                    break;

            }

            return rnt;

        }

        public int TitleToNumber(string s)

        {

            var list = s.ToList();

            var count = list.Count;

            int sum = ;

            for (int i = ; i < list.Count; i++)

            {

                var mi = count - i - ;

                //mi是幂  * pow(26,mi)

                int num = ConvertToC(list[i]);

                sum += num * Convert.ToInt32(Math.Pow(, mi));

            }

            Console.WriteLine(sum);

            return sum;

        }

}

 class Solution:

     def titleToNumber(self, s: 'str') -> 'int':

         s = s.upper()

         n = len(s)

         sums =

         k =

         for i in range(n-,-,-):

             asci = ord(s[i]) -

             sums +=  ** k * asci

             k +=

         return sums