durankulak numbers

using System;
using System.Collections.Generic;
using System.Text;
using System.Text.RegularExpressions;

class KaspichanNumbers2
{
    static void Main()
    {
        string input = Console.ReadLine();
        Stack<string> num168 = new Stack<string>();
        foreach (Match number in Regex.Matches(input,"[a-z]?[A-Z]"))
        {
            num168.Push(number.Value);
        }

        long number10 = 0;
        int position = 0;
        while (num168.Count > 0)
        {
            string currStr = num168.Pop();
            if (currStr.Length == 1)
            {
                number10 += (currStr[0] - 'A') * (long)Math.Pow(168,position);
            }
            else
            {
                number10 += ((currStr[1] - 'A') + ((currStr[0] - 'a')+1)*26) * (long)Math.Pow(168, position);
            }
            position++;
        }
        Console.WriteLine(number10);
    }
}