import java.math.BigInteger;
import java.util.Scanner;

public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		BigInteger dogs = new BigInteger(String.valueOf(sc.next()));
		BigInteger[] results;
		StringBuilder result = new StringBuilder("");

		results = dogs.divideAndRemainder(new BigInteger("1"));
		while(results[0].compareTo(new BigInteger("0")) != 0) {
			dogs = dogs.subtract(new BigInteger("1"));
			results = dogs.divideAndRemainder(new BigInteger("26"));
			dogs = results[0];
			result.insert(0,(char)('a' + (char)results[1].intValue()));
		}

		System.out.println(result.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