using System;

public class Program {
    public static void Main() {
        long n = long.Parse(Console.ReadLine());
        string str = ((char)('A'+n%26)).ToString();
        n /= 26;
        while (n > 0) {
            n--;
            str = ((char)('A'+n%26)).ToString() + str;
            n /= 26;
        }
        Console.WriteLine(str);
    }
}