import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long n = sc.nextLong();
        StringBuilder sb = new StringBuilder();
        int i = 1;
        while (i <= 11) {
            if (n > Math.pow(26, i)) {
                n -= Math.pow(26, i++);
                continue;
            }
            n -= 1;
            for (int j = 0; j < i; j++) {
                sb.append((char) (n % 26 + 'a'));
                n /= 26;
            }
            break;
        }
        System.out.println(sb.reverse());
    }

} 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();
        StringBuilder sb = new StringBuilder();
        int i = 1;
        while (i <= 11) {
            if (n > Math.pow(26, i)) {
                n -= Math.pow(26, i++);
                continue;
            }
            n -= 1;
            for (int j = 0; j < i; j++) {
                sb.append((char) (n % 26 + 'a'));
                n /= 26;
            }
            break;
        }
        System.out.println(sb.reverse());
    }

} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long n = sc.nextLong();
        StringBuilder sb = new StringBuilder();
        int i = 1;
        while (i <= 11) {
            if (n > Math.pow(26, i)) {
                n -= Math.pow(26, i++);
                continue;
            }
            n -= 1;
            for (int j = 0; j < i; j++) {
                sb.append((char) (n % 26 + 'a'));
                n /= 26;
            }
            break;
        }
        System.out.println(sb.reverse());
    } main {
        Scanner sc = new Scanner(System.in);
        long n = sc.nextLong();
        StringBuilder sb = new StringBuilder();
        int i = 1;
        while (i <= 11) {
            if (n > Math.pow(26, i)) {
                n -= Math.pow(26, i++);
                continue;
            }
            n -= 1;
            for (int j = 0; j < i; j++) {
                sb.append((char) (n % 26 + 'a'));
                n /= 26;
            }
            break;
        }
        System.out.println(sb.reverse());
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) long n = sc.nextLong(); n sc.nextLong() sc.nextLong sc StringBuilder sb = new StringBuilder(); sb new StringBuilder() int i = 1; i 1 while (i <= 11) {
            if (n > Math.pow(26, i)) {
                n -= Math.pow(26, i++);
                continue;
            }
            n -= 1;
            for (int j = 0; j < i; j++) {
                sb.append((char) (n % 26 + 'a'));
                n /= 26;
            }
            break;
        } i <= 11 i 11 {
            if (n > Math.pow(26, i)) {
                n -= Math.pow(26, i++);
                continue;
            }
            n -= 1;
            for (int j = 0; j < i; j++) {
                sb.append((char) (n % 26 + 'a'));
                n /= 26;
            }
            break;
        } if (n > Math.pow(26, i)) {
                n -= Math.pow(26, i++);
                continue;
            } n > Math.pow(26, i) n Math.pow(26, i) Math.pow Math 26 i {
                n -= Math.pow(26, i++);
                continue;
            } n -= Math.pow(26, i++) n Math.pow(26, i++) Math.pow Math 26 i++ i continue; n -= 1 n 1 for (int j = 0; j < i; j++) {
                sb.append((char) (n % 26 + 'a'));
                n /= 26;
            } int j = 0; int j = 0; j 0 j < i j i j++ j++ j {
                sb.append((char) (n % 26 + 'a'));
                n /= 26;
            } {
                sb.append((char) (n % 26 + 'a'));
                n /= 26;
            } sb.append((char) (n % 26 + 'a')) sb.append sb (char) (n % 26 + 'a') n % 26 n 26 'a' n /= 26 n 26 break; System.out.println(sb.reverse()) System.out.println System.out System System.out sb.reverse() sb.reverse sb String[] args args public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long n = sc.nextLong();
        StringBuilder sb = new StringBuilder();
        int i = 1;
        while (i <= 11) {
            if (n > Math.pow(26, i)) {
                n -= Math.pow(26, i++);
                continue;
            }
            n -= 1;
            for (int j = 0; j < i; j++) {
                sb.append((char) (n % 26 + 'a'));
                n /= 26;
            }
            break;
        }
        System.out.println(sb.reverse());
    }

} public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long n = sc.nextLong();
        StringBuilder sb = new StringBuilder();
        int i = 1;
        while (i <= 11) {
            if (n > Math.pow(26, i)) {
                n -= Math.pow(26, i++);
                continue;
            }
            n -= 1;
            for (int j = 0; j < i; j++) {
                sb.append((char) (n % 26 + 'a'));
                n /= 26;
            }
            break;
        }
        System.out.println(sb.reverse());
    }

} Main
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long n = sc.nextLong();
        StringBuilder sb = new StringBuilder();
        int i = 1;
        while (i <= 11) {
            if (n > Math.pow(26, i)) {
                n -= Math.pow(26, i++);
                continue;
            }
            n -= 1;
            for (int j = 0; j < i; j++) {
                sb.append((char) (n % 26 + 'a'));
                n /= 26;
            }
            break;
        }
        System.out.println(sb.reverse());
    }

}
