Durankulak_Numbers

using System;

class DurankulakNumbers
{
    static void Main()
    {
        string input = Console.ReadLine();
        int count = 0;
        for (int i = 0; i < input.Length; i++)
        {
            char letter = input[i];
            if (char.IsUpper(letter)) count++;
        }
        string[] letters = new string[count];
        ulong[] values = new ulong[count];
        count = 0;

        for (int i = 0; i < input.Length; i++)
        {
            char letter = input[i];
            if (char.IsUpper(letter))
            {
                letters[count] = letter.ToString();
            }
            else
            {
                char next = input[i+1];
                letters[count] = letter.ToString() + next.ToString();
                i++;
            }
            count++;
        }

        for (int i = 0; i < letters.Length; i++)
        {
            if (letters[i].Length == 1)
            {
                values[i] = (ulong)(char.Parse(letters[i]) - 65);
            }
            else
            {
                char first = char.ToUpper(letters[i][0]);
                char second = letters[i][1];
                ulong firstNum = (ulong)(first - 64);
                ulong secondNum = (ulong)(second - 65);
                values[i] = (ulong)(secondNum * (ulong)Math.Pow(26, 0)) +
                    (ulong)(firstNum * (ulong)Math.Pow(26, 1));
            }
        }

        ulong result = 0;
        int power = 0;
        for (int i = values.Length - 1; i >= 0; i--)
        {
            result += values[i] * (ulong)Math.Pow(168, power);
            power++;
        }
        Console.WriteLine(result);
    }
}