// 提出時に消す


import java.util.Scanner;

// 提出時にMainに変更する
public class Main {

    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);

        long n = sc.nextLong();

        StringBuilder ans = new StringBuilder();

        while (n != 0) {
            n--;
            ans.append((char) ('a' + n % 26));
            n /= 26;
        }

        ans = ans.reverse();

        System.out.println(ans);

        sc.close();
    }
}
/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