import java.lang.*;
import java.util.*;

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

        String str = scan.next();

        long num = Long.parseLong(str);
        num--;

        ArrayList<Long> list = new ArrayList<>();

        while (true) {
            list.add(0, num % 26);
            if (num / 26 == 0) break;
            else {
                num /= 26;
                num--;
            }
        }

        for (long i : list) {
            System.out.print((char)(i + 'a'));
        }
        System.out.println();
    }
}

/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