
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;

import java.math.BigInteger;
import java.util.*;
import java.util.stream.Collectors;

public class Main {
    long MOD = (long) 1e9 + 7;

    InputStream in;
    OutputStream out;

    public Main() {
        this(System.in, System.out);
    }

    public Main(InputStream in, OutputStream out) {
        this.in = in;
        this.out = out;
    }

    void run() {
        Scanner sc = new Scanner(this.in);
        PrintWriter out = new PrintWriter(this.out);

        // write your code
        long n = sc.nextLong();
        LinkedList<String> ans = new LinkedList<>();

        do {
            n--;
            ans.addFirst("" + (char)('a' + n % 26));
            n /= 26;
        } while (n != 0);


        out.println(String.join("", ans));

        out.flush();
    }

    void debug(Object... os) {
        System.err.println(Arrays.deepToString(os));
    }

    public static void main(String[] args) {
        new Main().run();
    }
} import java.io.InputStream; InputStream java.io import java.io.OutputStream; OutputStream java.io import java.io.PrintWriter; PrintWriter java.io import java.math.BigInteger; BigInteger java.math import java.util.*; util.* java import java.util.stream.Collectors; Collectors java.util.stream public class Main {
    long MOD = (long) 1e9 + 7;

    InputStream in;
    OutputStream out;

    public Main() {
        this(System.in, System.out);
    }

    public Main(InputStream in, OutputStream out) {
        this.in = in;
        this.out = out;
    }

    void run() {
        Scanner sc = new Scanner(this.in);
        PrintWriter out = new PrintWriter(this.out);

        // write your code
        long n = sc.nextLong();
        LinkedList<String> ans = new LinkedList<>();

        do {
            n--;
            ans.addFirst("" + (char)('a' + n % 26));
            n /= 26;
        } while (n != 0);


        out.println(String.join("", ans));

        out.flush();
    }

    void debug(Object... os) {
        System.err.println(Arrays.deepToString(os));
    }

    public static void main(String[] args) {
        new Main().run();
    }
} Main long MOD = (long) 1e9 + 7; MOD (long) 1e9 + 7 (long) 1e9 7 InputStream in; in OutputStream out; out public Main() {
        this(System.in, System.out);
    } Main {
        this(System.in, System.out);
    } this(System.in, System.out) this System.in System System.in System.out System System.out public Main(InputStream in, OutputStream out) {
        this.in = in;
        this.out = out;
    } Main {
        this.in = in;
        this.out = out;
    } this.in = in this.in this this.in in this.out = out this.out this this.out out InputStream in in OutputStream out out void run() {
        Scanner sc = new Scanner(this.in);
        PrintWriter out = new PrintWriter(this.out);

        // write your code
        long n = sc.nextLong();
        LinkedList<String> ans = new LinkedList<>();

        do {
            n--;
            ans.addFirst("" + (char)('a' + n % 26));
            n /= 26;
        } while (n != 0);


        out.println(String.join("", ans));

        out.flush();
    } run {
        Scanner sc = new Scanner(this.in);
        PrintWriter out = new PrintWriter(this.out);

        // write your code
        long n = sc.nextLong();
        LinkedList<String> ans = new LinkedList<>();

        do {
            n--;
            ans.addFirst("" + (char)('a' + n % 26));
            n /= 26;
        } while (n != 0);


        out.println(String.join("", ans));

        out.flush();
    } Scanner sc = new Scanner(this.in); sc new Scanner(this.in) PrintWriter out = new PrintWriter(this.out); out new PrintWriter(this.out) long n = sc.nextLong(); n sc.nextLong() sc.nextLong sc LinkedList<String> ans = new LinkedList<>(); ans new LinkedList<>() do {
            n--;
            ans.addFirst("" + (char)('a' + n % 26));
            n /= 26;
        } while (n != 0); n != 0 n 0 {
            n--;
            ans.addFirst("" + (char)('a' + n % 26));
            n /= 26;
        } n-- n ans.addFirst("" + (char)('a' + n % 26)) ans.addFirst ans "" + (char)('a' + n % 26) "" (char)('a' + n % 26) 'a' n % 26 n 26 n /= 26 n 26 out.println(String.join("", ans)) out.println out String.join("", ans) String.join String "" ans out.flush() out.flush out void debug(Object... os) {
        System.err.println(Arrays.deepToString(os));
    } debug {
        System.err.println(Arrays.deepToString(os));
    } System.err.println(Arrays.deepToString(os)) System.err.println System.err System System.err Arrays.deepToString(os) Arrays.deepToString Arrays os Object... os os public static void main(String[] args) {
        new Main().run();
    } main {
        new Main().run();
    } new Main().run() new Main().run new Main() String[] args args public class Main {
    long MOD = (long) 1e9 + 7;

    InputStream in;
    OutputStream out;

    public Main() {
        this(System.in, System.out);
    }

    public Main(InputStream in, OutputStream out) {
        this.in = in;
        this.out = out;
    }

    void run() {
        Scanner sc = new Scanner(this.in);
        PrintWriter out = new PrintWriter(this.out);

        // write your code
        long n = sc.nextLong();
        LinkedList<String> ans = new LinkedList<>();

        do {
            n--;
            ans.addFirst("" + (char)('a' + n % 26));
            n /= 26;
        } while (n != 0);


        out.println(String.join("", ans));

        out.flush();
    }

    void debug(Object... os) {
        System.err.println(Arrays.deepToString(os));
    }

    public static void main(String[] args) {
        new Main().run();
    }
} public class Main {
    long MOD = (long) 1e9 + 7;

    InputStream in;
    OutputStream out;

    public Main() {
        this(System.in, System.out);
    }

    public Main(InputStream in, OutputStream out) {
        this.in = in;
        this.out = out;
    }

    void run() {
        Scanner sc = new Scanner(this.in);
        PrintWriter out = new PrintWriter(this.out);

        // write your code
        long n = sc.nextLong();
        LinkedList<String> ans = new LinkedList<>();

        do {
            n--;
            ans.addFirst("" + (char)('a' + n % 26));
            n /= 26;
        } while (n != 0);


        out.println(String.join("", ans));

        out.flush();
    }

    void debug(Object... os) {
        System.err.println(Arrays.deepToString(os));
    }

    public static void main(String[] args) {
        new Main().run();
    }
} Main

import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;

import java.math.BigInteger;
import java.util.*;
import java.util.stream.Collectors;

public class Main {
    long MOD = (long) 1e9 + 7;

    InputStream in;
    OutputStream out;

    public Main() {
        this(System.in, System.out);
    }

    public Main(InputStream in, OutputStream out) {
        this.in = in;
        this.out = out;
    }

    void run() {
        Scanner sc = new Scanner(this.in);
        PrintWriter out = new PrintWriter(this.out);

        // write your code
        long n = sc.nextLong();
        LinkedList<String> ans = new LinkedList<>();

        do {
            n--;
            ans.addFirst("" + (char)('a' + n % 26));
            n /= 26;
        } while (n != 0);


        out.println(String.join("", ans));

        out.flush();
    }

    void debug(Object... os) {
        System.err.println(Arrays.deepToString(os));
    }

    public static void main(String[] args) {
        new Main().run();
    }
}