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

class Magatro
{
    static void Main()
    {
        string ans = "";
        long N = long.Parse(Console.ReadLine());
        char[] D = "ABCDEFGHIJKLMNOPQRSTUVWXYZ".ToArray();
        
        while (N>=0)
        {

            long q = N % 26;
            ans = D[q] + ans;
            N /= 26;
            N--;
        }
        Console.WriteLine(ans);
    }

}