import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long N = sc.nextLong();
        System.out.println(calc(N));
        sc.close();
        return;
    }

    static String calc(long N) {
        if (N == 0) {
            return "";
        }
        N--;
        return calc(N / 26) + (char) ('a' + N % 26);
    }
} 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();
        System.out.println(calc(N));
        sc.close();
        return;
    }

    static String calc(long N) {
        if (N == 0) {
            return "";
        }
        N--;
        return calc(N / 26) + (char) ('a' + N % 26);
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long N = sc.nextLong();
        System.out.println(calc(N));
        sc.close();
        return;
    } main {
        Scanner sc = new Scanner(System.in);
        long N = sc.nextLong();
        System.out.println(calc(N));
        sc.close();
        return;
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) long N = sc.nextLong(); N sc.nextLong() sc.nextLong sc System.out.println(calc(N)) System.out.println System.out System System.out calc(N) calc N sc.close() sc.close sc return; String[] args args static String calc(long N) {
        if (N == 0) {
            return "";
        }
        N--;
        return calc(N / 26) + (char) ('a' + N % 26);
    } calc {
        if (N == 0) {
            return "";
        }
        N--;
        return calc(N / 26) + (char) ('a' + N % 26);
    } if (N == 0) {
            return "";
        } N == 0 N 0 {
            return "";
        } return ""; "" N-- N return calc(N / 26) + (char) ('a' + N % 26); calc(N / 26) + (char) ('a' + N % 26) calc(N / 26) calc N / 26 N 26 (char) ('a' + N % 26) 'a' N % 26 N 26 long N N public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long N = sc.nextLong();
        System.out.println(calc(N));
        sc.close();
        return;
    }

    static String calc(long N) {
        if (N == 0) {
            return "";
        }
        N--;
        return calc(N / 26) + (char) ('a' + N % 26);
    }
} public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long N = sc.nextLong();
        System.out.println(calc(N));
        sc.close();
        return;
    }

    static String calc(long N) {
        if (N == 0) {
            return "";
        }
        N--;
        return calc(N / 26) + (char) ('a' + N % 26);
    }
} Main
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long N = sc.nextLong();
        System.out.println(calc(N));
        sc.close();
        return;
    }

    static String calc(long N) {
        if (N == 0) {
            return "";
        }
        N--;
        return calc(N / 26) + (char) ('a' + N % 26);
    }
}
