import java.util.Scanner;


public class Main {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);
		long n = sc.nextLong();
		StringBuilder ans = new StringBuilder();

		while(0 < n) {
			n--;
			ans.append((char) (n % 26 + 97));
			n /= 26;
		}

		System.out.println(ans.reverse());
		sc.close();
	}

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

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);
		long n = sc.nextLong();
		StringBuilder ans = new StringBuilder();

		while(0 < n) {
			n--;
			ans.append((char) (n % 26 + 97));
			n /= 26;
		}

		System.out.println(ans.reverse());
		sc.close();
	}

} Main public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);
		long n = sc.nextLong();
		StringBuilder ans = new StringBuilder();

		while(0 < n) {
			n--;
			ans.append((char) (n % 26 + 97));
			n /= 26;
		}

		System.out.println(ans.reverse());
		sc.close();
	} main {

		Scanner sc = new Scanner(System.in);
		long n = sc.nextLong();
		StringBuilder ans = new StringBuilder();

		while(0 < n) {
			n--;
			ans.append((char) (n % 26 + 97));
			n /= 26;
		}

		System.out.println(ans.reverse());
		sc.close();
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) long n = sc.nextLong(); n sc.nextLong() sc.nextLong sc StringBuilder ans = new StringBuilder(); ans new StringBuilder() while(0 < n) {
			n--;
			ans.append((char) (n % 26 + 97));
			n /= 26;
		} 0 < n 0 n {
			n--;
			ans.append((char) (n % 26 + 97));
			n /= 26;
		} n-- n ans.append((char) (n % 26 + 97)) ans.append ans (char) (n % 26 + 97) n % 26 n 26 97 n /= 26 n 26 System.out.println(ans.reverse()) System.out.println System.out System System.out ans.reverse() ans.reverse ans sc.close() sc.close sc String[] args args public class Main {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);
		long n = sc.nextLong();
		StringBuilder ans = new StringBuilder();

		while(0 < n) {
			n--;
			ans.append((char) (n % 26 + 97));
			n /= 26;
		}

		System.out.println(ans.reverse());
		sc.close();
	}

} public class Main {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);
		long n = sc.nextLong();
		StringBuilder ans = new StringBuilder();

		while(0 < n) {
			n--;
			ans.append((char) (n % 26 + 97));
			n /= 26;
		}

		System.out.println(ans.reverse());
		sc.close();
	}

} Main
import java.util.Scanner;


public class Main {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);
		long n = sc.nextLong();
		StringBuilder ans = new StringBuilder();

		while(0 < n) {
			n--;
			ans.append((char) (n % 26 + 97));
			n /= 26;
		}

		System.out.println(ans.reverse());
		sc.close();
	}

}