import java.util.*;
public class Main {

	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		long n = scan.nextLong();
		ArrayList<Character> list = new ArrayList<Character>();
		while(n > 0) {
			int amari = (int) (n % 26);
			list.add(toS(amari));
			if(n % 26 == 0) {
				n -= 1;
			}
			n /= 26;
		}
		Collections.reverse(list);
		Character[] name = list.toArray(new Character[list.size()]);
		char[] name2 = new char[list.size()];
		for(int i = 0; i < list.size(); i++) {
			name2[i] = (char)name[i];
		}
		String na = new String(name2);
		System.out.println(na);
	}
	
	public static char toS(int n) {
		if(n == 0) {
			return 'z';
		}
		int a = 'a' - 1;
		a = n + a;
		return (char)a;
	}
}

/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz