using System.Linq;
using System.Collections.Generic;
using System;

public class Hello
{
    static void Main()
    {
        var n = long.Parse(Console.ReadLine().Trim());
        var a = getL(n);
        getAns(a);
    }
    static void getAns(List<int> a)
    {
        var ans = "";
        var k = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        ans += k[a[0]];
        for (int i = 1; i < a.Count(); i++)
        {
            var x = a[i] - 1 >= 0 ? a[i] - 1 : a[i] + 25;
            ans += k[x];
        }
        var ans2 = ans.ToCharArray();
        Array.Reverse(ans2);
        Console.WriteLine(new string(ans2));
    }
    static List<int> getL(long n)
    {
        var res = new List<int>();
        var t = n;
        while (true)
        {
            res.Add((int)(t % 26));
            t /= 26;
            if (t < 26)
            {
                if (t != 0) res.Add((int)t);
                break;
            }
        }
        return res;
    }
}