import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Scanner;

public class Main {
	public static void main(String[] args){
		try(Scanner sc = new Scanner(System.in)) {
			
			long n = sc.nextLong();
			
			List<String> initials = new ArrayList<>();
			
			long current = n;
			
			while(current > 0) {
				
				current--;
				
				long residual = current % 26;
				current = (current - residual) / 26;
				
				char initial = (char) ('a' + residual);				
				String initStr = String.valueOf(initial);
				
				initials.add(initStr);
				
			}
			
			Collections.reverse(initials);
			StringBuilder sb = new StringBuilder();
			for(String s : initials) {
				sb.append(s);
			}
			
			System.out.println(sb.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