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

namespace ConsoleApplication3
{
	class Program
	{
		private static readonly List<char> ConvertTable = Enumerable.Range(0x41, 26).Select(x => (char) x).ToList();
		static void Main(string[] args)
		{

			var n = long.Parse(Console.ReadLine());

			var fac = 26;

			var buff = new List<char>();

			buff.Add(ConvertTable[(int)(n%26)]);
			while ((n /= fac) != 0)
			{
				n--;
				buff.Add(ConvertTable[(int) (n%26)]);
			}

			buff.Reverse();
			Console.WriteLine(buff.Aggregate(new StringBuilder(), (b, c) => b.Append(c)).ToString());

		}
	}
}