import java.util.*;
import java.util.Collections;
public class Main {
	public static void main(String[] args){	
      Scanner sc = null;
      sc = new Scanner(System.in);
      long N = sc.nextLong();
      String ans = "";
     
      while(N-- > 0){
        ans = (char)('a' + (N%26)) + ans;
        N /= 26;
      }
      System.out.println(ans);
    }
}
/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