import java.util.Scanner;

public class Main {

	/** 英文字のアルファベット */
	private static final char[] ALPHABET = "abcdefghijklmnopqrstuvwxyz".toCharArray();

	public static void main(String[] args) {
		try (Scanner scanner = new Scanner(System.in)) {
			long n = scanner.nextLong();
			StringBuilder sb = new StringBuilder();
			while (n > 0) {
				sb.append(ALPHABET[(int) ((n - 1) % 26)]);
				n = (n - 1) / 26;
			}
			System.out.println(sb.reverse().toString());
		}
	}
}

/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