import java.util.Scanner;

public class Main {

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

		long n = Long.parseLong(sc.next());

		int c = 'a';

		StringBuilder sb = new StringBuilder();
		while (n != 0) {
			long remainder = (n - 1) % 26;
			sb.append((char) (c + remainder));

			n = (n - remainder + 1) / 26;
		}

		System.out.println(sb.reverse());
	}

}

/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