ExcelColumns

using System;

class ExcelColumns
{
    static void Main()
    {
        int n = int.Parse(Console.ReadLine());

        long index = 0;
        for (int i = n - 1; i >= 0; i--)
        {
            string letter = Console.ReadLine();
            int ch = Convert.ToChar(letter) - '@';
            index += ch * (long)Math.Pow(26, i);
        }
        Console.WriteLine(index);
    }
}