import java.util.*;

public class Main {
	 
	  public static String getKey(Long index){
		String colCode = "";
		char key='a';
		Long loop = index / 26;
		if(loop>0){
			colCode += getKey(loop-1);
		}
		key = (char) (key+index%26);
		colCode += key;
		return colCode;
	}

		public static void main(String[] args) {
	        Scanner sc = new Scanner(System.in);
	        Long n = sc.nextLong();
	        System.out.println(getKey(n-1)); 
		}
}
/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