import java.util.Scanner;

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

        long N = scanner.nextLong();
        long[] num = new long[50];
        int k = 0;
        while(N > 0) {
            num[++k] = (N - 1) % 26;
            N--;
            N /= 26;
        }
        String ans = "";
        for (int i = k; i > 0; i--) {
            char c = (char) (97 + num[i]);
            ans += c;
        }
        System.out.println(ans);
    }
}
/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