import java.math.BigInteger;
import java.util.Scanner;

class Main {

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

		long n = sc.nextLong();
		sc.close();

		StringBuilder sb = new StringBuilder();
		while (n > 0) {
			n -= 1;
			sb.append((char) ('a' + n % 26));
			n /= 26;
		}
		System.out.println(sb.reverse().toString());
	}
} import java.math.BigInteger; BigInteger java.math import java.util.Scanner; Scanner java.util class Main {

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

		long n = sc.nextLong();
		sc.close();

		StringBuilder sb = new StringBuilder();
		while (n > 0) {
			n -= 1;
			sb.append((char) ('a' + n % 26));
			n /= 26;
		}
		System.out.println(sb.reverse().toString());
	}
} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		long n = sc.nextLong();
		sc.close();

		StringBuilder sb = new StringBuilder();
		while (n > 0) {
			n -= 1;
			sb.append((char) ('a' + n % 26));
			n /= 26;
		}
		System.out.println(sb.reverse().toString());
	} main {
		Scanner sc = new Scanner(System.in);

		long n = sc.nextLong();
		sc.close();

		StringBuilder sb = new StringBuilder();
		while (n > 0) {
			n -= 1;
			sb.append((char) ('a' + n % 26));
			n /= 26;
		}
		System.out.println(sb.reverse().toString());
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) long n = sc.nextLong(); n sc.nextLong() sc.nextLong sc sc.close() sc.close sc StringBuilder sb = new StringBuilder(); sb new StringBuilder() while (n > 0) {
			n -= 1;
			sb.append((char) ('a' + n % 26));
			n /= 26;
		} n > 0 n 0 {
			n -= 1;
			sb.append((char) ('a' + n % 26));
			n /= 26;
		} n -= 1 n 1 sb.append((char) ('a' + n % 26)) sb.append sb (char) ('a' + n % 26) 'a' n % 26 n 26 n /= 26 n 26 System.out.println(sb.reverse().toString()) System.out.println System.out System System.out sb.reverse().toString() sb.reverse().toString sb.reverse() sb.reverse sb String[] args args
import java.math.BigInteger;
import java.util.Scanner;

class Main {

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

		long n = sc.nextLong();
		sc.close();

		StringBuilder sb = new StringBuilder();
		while (n > 0) {
			n -= 1;
			sb.append((char) ('a' + n % 26));
			n /= 26;
		}
		System.out.println(sb.reverse().toString());
	}
}