import java.io.*;
import java.math.*;
import java.util.*;
public class Main {
 
	public static void main(String[] args) {
		Scanner input = new Scanner(System.in);
		long N = input.nextLong();
		String ans = "";
		Stack<Character> seq = new Stack<Character>();
		while (N>0) {
			N--;
			char cur = (char)(N%26+97);
			seq.push(cur);
			N/=26;
		}
		while (!seq.isEmpty()) {
			char cur = seq.pop();
			System.out.print(cur);
		}
	}
}
/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