import java.util.Scanner;
import java.util.Arrays;

public class Main{
	public static void main(String args[]){
      Scanner scan = new Scanner(System.in);
      long N = scan.nextLong();

      String res = "";
      //Nが0ではない間
      while(N != 0){
          N--;
          res += (char)('a' + (N % 26));
          N /= 26;
      }
      //文字列を反転
      StringBuilder builder = new StringBuilder(res);
      String result = builder.reverse().toString();

      System.out.println(result);
    }
}
/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