import java.util.Scanner;

public class Main {

    public static final int MOD = 1000000007;

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

    public static final int MOD = 1000000007;

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long n = Long.parseLong(sc.next());
        StringBuilder sb = new StringBuilder();
        while (n > 0) {
            n--;
            long mod = n % 26;
            sb.append((char) ('a' + mod));
            n /= 26;
        }
        System.out.println(sb.reverse().toString());
    }
} Main public static final int MOD = 1000000007; MOD 1000000007 public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long n = Long.parseLong(sc.next());
        StringBuilder sb = new StringBuilder();
        while (n > 0) {
            n--;
            long mod = n % 26;
            sb.append((char) ('a' + mod));
            n /= 26;
        }
        System.out.println(sb.reverse().toString());
    } main {
        Scanner sc = new Scanner(System.in);
        long n = Long.parseLong(sc.next());
        StringBuilder sb = new StringBuilder();
        while (n > 0) {
            n--;
            long mod = n % 26;
            sb.append((char) ('a' + mod));
            n /= 26;
        }
        System.out.println(sb.reverse().toString());
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) long n = Long.parseLong(sc.next()); n Long.parseLong(sc.next()) Long.parseLong Long sc.next() sc.next sc StringBuilder sb = new StringBuilder(); sb new StringBuilder() while (n > 0) {
            n--;
            long mod = n % 26;
            sb.append((char) ('a' + mod));
            n /= 26;
        } n > 0 n 0 {
            n--;
            long mod = n % 26;
            sb.append((char) ('a' + mod));
            n /= 26;
        } n-- n long mod = n % 26; mod n % 26 n 26 sb.append((char) ('a' + mod)) sb.append sb (char) ('a' + mod) 'a' mod 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 public class Main {

    public static final int MOD = 1000000007;

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

    public static final int MOD = 1000000007;

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

public class Main {

    public static final int MOD = 1000000007;

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