import java.util.Scanner;

public class Main {

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

		long n = scanner.nextLong();
		while (n-- > 0){
			s = (char)('a' + (n%26)) + s;
			n /= 26;
		}
		System.out.println(s);
	}

} import java.util.Scanner; Scanner java.util public class Main {

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

		long n = scanner.nextLong();
		while (n-- > 0){
			s = (char)('a' + (n%26)) + s;
			n /= 26;
		}
		System.out.println(s);
	}

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

		long n = scanner.nextLong();
		while (n-- > 0){
			s = (char)('a' + (n%26)) + s;
			n /= 26;
		}
		System.out.println(s);
	} main {
		Scanner scanner = new Scanner(System.in);
		String s = "";

		long n = scanner.nextLong();
		while (n-- > 0){
			s = (char)('a' + (n%26)) + s;
			n /= 26;
		}
		System.out.println(s);
	} Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) String s = ""; s "" long n = scanner.nextLong(); n scanner.nextLong() scanner.nextLong scanner while (n-- > 0){
			s = (char)('a' + (n%26)) + s;
			n /= 26;
		} n-- > 0 n-- n 0 {
			s = (char)('a' + (n%26)) + s;
			n /= 26;
		} s = (char)('a' + (n%26)) + s s (char)('a' + (n%26)) + s (char)('a' + (n%26)) 'a' (n%26) n 26 s n /= 26 n 26 System.out.println(s) System.out.println System.out System System.out s String[] args args public class Main {

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

		long n = scanner.nextLong();
		while (n-- > 0){
			s = (char)('a' + (n%26)) + s;
			n /= 26;
		}
		System.out.println(s);
	}

} public class Main {

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

		long n = scanner.nextLong();
		while (n-- > 0){
			s = (char)('a' + (n%26)) + s;
			n /= 26;
		}
		System.out.println(s);
	}

} Main
import java.util.Scanner;

public class Main {

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

		long n = scanner.nextLong();
		while (n-- > 0){
			s = (char)('a' + (n%26)) + s;
			n /= 26;
		}
		System.out.println(s);
	}

}
