import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long n = sc.nextLong();
		StringBuilder sb = new StringBuilder();
		while (n > 0L) {
			--n;
			sb.append((char) ('a' + n % 26L));
			n /= 26L;
		}
		sb.reverse();
		System.out.println(sb.toString());
	}
} 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 sb = new StringBuilder();
		while (n > 0L) {
			--n;
			sb.append((char) ('a' + n % 26L));
			n /= 26L;
		}
		sb.reverse();
		System.out.println(sb.toString());
	}
} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long n = sc.nextLong();
		StringBuilder sb = new StringBuilder();
		while (n > 0L) {
			--n;
			sb.append((char) ('a' + n % 26L));
			n /= 26L;
		}
		sb.reverse();
		System.out.println(sb.toString());
	} main {
		Scanner sc = new Scanner(System.in);
		long n = sc.nextLong();
		StringBuilder sb = new StringBuilder();
		while (n > 0L) {
			--n;
			sb.append((char) ('a' + n % 26L));
			n /= 26L;
		}
		sb.reverse();
		System.out.println(sb.toString());
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) long n = sc.nextLong(); n sc.nextLong() sc.nextLong sc StringBuilder sb = new StringBuilder(); sb new StringBuilder() while (n > 0L) {
			--n;
			sb.append((char) ('a' + n % 26L));
			n /= 26L;
		} n > 0L n 0L {
			--n;
			sb.append((char) ('a' + n % 26L));
			n /= 26L;
		} --n n sb.append((char) ('a' + n % 26L)) sb.append sb (char) ('a' + n % 26L) 'a' n % 26L n 26L n /= 26L n 26L sb.reverse() sb.reverse sb System.out.println(sb.toString()) System.out.println System.out System System.out sb.toString() sb.toString sb String[] args args public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long n = sc.nextLong();
		StringBuilder sb = new StringBuilder();
		while (n > 0L) {
			--n;
			sb.append((char) ('a' + n % 26L));
			n /= 26L;
		}
		sb.reverse();
		System.out.println(sb.toString());
	}
} public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long n = sc.nextLong();
		StringBuilder sb = new StringBuilder();
		while (n > 0L) {
			--n;
			sb.append((char) ('a' + n % 26L));
			n /= 26L;
		}
		sb.reverse();
		System.out.println(sb.toString());
	}
} 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 sb = new StringBuilder();
		while (n > 0L) {
			--n;
			sb.append((char) ('a' + n % 26L));
			n /= 26L;
		}
		sb.reverse();
		System.out.println(sb.toString());
	}
}
