import java.util.*;
import java.io.*;
public class Main{
        public static void main(String[] args){
                Scanner sc = new Scanner(System.in);
                PrintWriter ou = new PrintWriter(System.out);
                long n = Long.parseLong(sc.next());
                sc.close();
                String s = "";
                boolean ebishu = true;
                while(ebishu){
                        if(n <= 0) ebishu = false;
                        else{
                                int i =(int) (n % (long)26);
                                if(i == 0) i += 26;
                                char q = (char)(i + 96);
                                s = q + s;
                                n--;
                                n /= 26;
                        }
                }
                ou.print(s + "\n");
                ou.flush();
        }
}
/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