import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long n = sc.nextLong();
		//System.out.println(n);
		String ans = "";
		while(n>0){
			n--;
			ans += (char)('a' + (n%26));
			//if(n<26) break;
			n = n/26;
		}
		for(int i=ans.length()-1 ; i>=0; i--){
			System.out.print(ans.charAt(i));
		}
		
	}

}
/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