import java.util.*;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		// 整数の入力
		long n = sc.nextLong();
      	ArrayList<Character> name = new ArrayList<>();

      	for(;n>0;){
         n -= 1;
         name.add((char)(n%26+97));
         n /= 26;
        }
      	String dog = "";
      	for(int i=name.size()-1;i>=0;i--){
          dog += String.valueOf(name.get(i));
        }
		// 出力
		System.out.println(dog);
	}
}
/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