import java.util.Scanner;

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

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