
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);
		long n = sc.nextLong();
		StringBuilder sb = new StringBuilder();

		while(n > 0) {
			n--;
			sb.append((char)( 'a' + n % 26 ) );  // sb.append((char)( 97 + n % 26 ) );
			n = n / 26;
			//System.out.println(sb);
		}

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

		sc.close();


	}
}
/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