package no327;

import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long n = sc.nextLong() + 1;
		long[] ans = new long[15];
		int l = 0;
		while(n > 0) {
			ans[l] += n % 26;
			if (ans[l] == 0) {
				ans[l] = 26;
				n -= 26;
			}
			l++;
			n /= 26;
		}
		for(int i=l-1;i>=0;i--) {
			System.out.print((char) (ans[i] - 1 + 'A'));
		}
		System.out.println();
	}

}