import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		long n = java.lang.Long.parseLong(sc.next());
		sc.close();
		String ans = "";

		while( n > 0) {
			n -= 1;
			ans += (char)('a' + n % 26);
			n /= 26;
		}
		
		for(int i = 0; i < ans.length(); i++) {
			System.out.print(ans.charAt(ans.length() - 1 - i));
		}
		System.out.println();
	}
} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		long n = java.lang.Long.parseLong(sc.next());
		sc.close();
		String ans = "";

		while( n > 0) {
			n -= 1;
			ans += (char)('a' + n % 26);
			n /= 26;
		}
		
		for(int i = 0; i < ans.length(); i++) {
			System.out.print(ans.charAt(ans.length() - 1 - i));
		}
		System.out.println();
	}
} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		long n = java.lang.Long.parseLong(sc.next());
		sc.close();
		String ans = "";

		while( n > 0) {
			n -= 1;
			ans += (char)('a' + n % 26);
			n /= 26;
		}
		
		for(int i = 0; i < ans.length(); i++) {
			System.out.print(ans.charAt(ans.length() - 1 - i));
		}
		System.out.println();
	} main {
		Scanner sc = new Scanner(System.in);
		
		long n = java.lang.Long.parseLong(sc.next());
		sc.close();
		String ans = "";

		while( n > 0) {
			n -= 1;
			ans += (char)('a' + n % 26);
			n /= 26;
		}
		
		for(int i = 0; i < ans.length(); i++) {
			System.out.print(ans.charAt(ans.length() - 1 - i));
		}
		System.out.println();
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) long n = java.lang.Long.parseLong(sc.next()); n java.lang.Long.parseLong(sc.next()) java.lang.Long.parseLong java.lang.Long java.lang java java.lang java.lang.Long sc.next() sc.next sc sc.close() sc.close sc String ans = ""; ans "" while( n > 0) {
			n -= 1;
			ans += (char)('a' + n % 26);
			n /= 26;
		} n > 0 n 0 {
			n -= 1;
			ans += (char)('a' + n % 26);
			n /= 26;
		} n -= 1 n 1 ans += (char)('a' + n % 26) ans (char)('a' + n % 26) 'a' n % 26 n 26 n /= 26 n 26 for(int i = 0; i < ans.length(); i++) {
			System.out.print(ans.charAt(ans.length() - 1 - i));
		} int i = 0; int i = 0; i 0 i < ans.length() i ans.length() ans.length ans i++ i++ i {
			System.out.print(ans.charAt(ans.length() - 1 - i));
		} {
			System.out.print(ans.charAt(ans.length() - 1 - i));
		} System.out.print(ans.charAt(ans.length() - 1 - i)) System.out.print System.out System System.out ans.charAt(ans.length() - 1 - i) ans.charAt ans ans.length() - 1 - i ans.length() - 1 - i ans.length() ans.length ans 1 i System.out.println() System.out.println System.out System System.out String[] args args public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		long n = java.lang.Long.parseLong(sc.next());
		sc.close();
		String ans = "";

		while( n > 0) {
			n -= 1;
			ans += (char)('a' + n % 26);
			n /= 26;
		}
		
		for(int i = 0; i < ans.length(); i++) {
			System.out.print(ans.charAt(ans.length() - 1 - i));
		}
		System.out.println();
	}
} public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		long n = java.lang.Long.parseLong(sc.next());
		sc.close();
		String ans = "";

		while( n > 0) {
			n -= 1;
			ans += (char)('a' + n % 26);
			n /= 26;
		}
		
		for(int i = 0; i < ans.length(); i++) {
			System.out.print(ans.charAt(ans.length() - 1 - i));
		}
		System.out.println();
	}
} Main
import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		long n = java.lang.Long.parseLong(sc.next());
		sc.close();
		String ans = "";

		while( n > 0) {
			n -= 1;
			ans += (char)('a' + n % 26);
			n /= 26;
		}
		
		for(int i = 0; i < ans.length(); i++) {
			System.out.print(ans.charAt(ans.length() - 1 - i));
		}
		System.out.println();
	}
}