import java.io.*;
import java.util.*;
public class Main{
	public static void main(String args[]) throws IOException{
               BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));	
		long N= Long.parseLong(reader.readLine());
		String res = "";
		while(N>0){
			N--;
			res =  (char)('a'+ N%26)+ res;
			N/=26;			
		}
		System.out.println(res);
	}
	private static String getCharForNumber(int i) {
    	char[] alphabet = "zabcdefghijklmnopqrstuvwxyz".toCharArray();
    	return Character.toString(alphabet[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