import java.util.Scanner;

public class Main {

	public static void main (String[] args) {
		Scanner sc = new Scanner(System.in);

		System.out.println(solve(sc.nextLong()));

		sc.close();
	}

	public static String solve (long n) {
		String ret = "";
		String[] alp = {"A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","R","S","T","U","V","W","X","Y","Z"};
		while (n >= alp.length) {
			ret = alp[(int) (n % alp.length)] + ret;
			n /= alp.length;
		}
		return alp[(int)n] + ret;
	}

}