import java.util.Scanner;

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

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