import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		long n = java.lang.Long.parseLong(sc.next());
		sc.close();
		String ans = "";

		while( n > 0) {
			n -= 1;
			ans += (char)('a' + n % 26);
			n /= 26;
		}
		
		for(int i = 0; i < ans.length(); i++) {
			System.out.print(ans.charAt(ans.length() - 1 - i));
		}
		System.out.println();
	}
}
/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