import java.io.*;
import java.util.*;

public class Main {

	static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

	public static int nextInt() throws IOException {
		return Integer.parseInt(br.readLine());
	}

	public static long nextLong() throws IOException {
		return Long.parseLong(br.readLine());
	}

	public static String next() throws IOException {
		return br.readLine();
	}

	public static int[] sortArr(int arr[]) throws IOException {
		ArrayList<Integer> a = new ArrayList<Integer>();
		for (int i : arr)
			a.add(i);

		Collections.sort(a);

		for (int i = 0; i < a.size(); i++)
			arr[i] = a.get(i);
		return arr;
	}

	public static int[] desortArr(int arr[]) throws IOException {
		ArrayList<Integer> a = new ArrayList<Integer>();
		for (int i : arr)
			a.add(i);

		Collections.sort(a, Collections.reverseOrder());

		for (int i = 0; i < a.size(); i++)
			arr[i] = a.get(i);
		return arr;
	}

	public static int[] nextArr() throws IOException {
		String elements[] = br.readLine().split(" ");
		int arr[] = new int[elements.length];
		for (int j = 0; j < elements.length; j++)
			arr[j] = Integer.parseInt(elements[j]);
		return arr;
	}

	public static void printArr(char arr[]) {
		for (int i = 0; i < arr.length; i++)
			System.out.print(arr[i] + " ");
	}

	public static void main(String[] args) throws IOException {

		int T = 1;
	
		while (T-- > 0) {
			long n = Long.parseLong(next());
			
			String s = "";

			while (n > 0) {
				n -= 1;
				s += (char) (97 + n % 26);
				n = n / 26;
			}
			System.out.println(new StringBuilder(s).reverse());
		}
	}

}

/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