import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Scanner;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author Ahmad Hamadneh
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        A solver = new A();
        solver.solve(1, in, out);
        out.close();
    }

    static class A {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            long x = in.nextLong();
            out.print(getString(x));
        }

        private static String getString(long n) {
            char[] buf = new char[(int) StrictMath.floor(StrictMath.log(25 * (n + 1)) / StrictMath.log(26))];
            for (int i = buf.length - 1; i >= 0; i--) {
                n--;
                buf[i] = (char) ('a' + n % 26);
                n /= 26;
            }
            return new String(buf);
        }

    }
}
 import java.io.OutputStream; OutputStream java.io import java.io.IOException; IOException java.io import java.io.InputStream; InputStream java.io import java.io.PrintWriter; PrintWriter java.io import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        A solver = new A();
        solver.solve(1, in, out);
        out.close();
    }

    static class A {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            long x = in.nextLong();
            out.print(getString(x));
        }

        private static String getString(long n) {
            char[] buf = new char[(int) StrictMath.floor(StrictMath.log(25 * (n + 1)) / StrictMath.log(26))];
            for (int i = buf.length - 1; i >= 0; i--) {
                n--;
                buf[i] = (char) ('a' + n % 26);
                n /= 26;
            }
            return new String(buf);
        }

    }
} Main public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        A solver = new A();
        solver.solve(1, in, out);
        out.close();
    } main {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        A solver = new A();
        solver.solve(1, in, out);
        out.close();
    } InputStream inputStream = System.in; inputStream System.in System System.in OutputStream outputStream = System.out; outputStream System.out System System.out Scanner in = new Scanner(inputStream); in new Scanner(inputStream) PrintWriter out = new PrintWriter(outputStream); out new PrintWriter(outputStream) A solver = new A(); solver new A() solver.solve(1, in, out) solver.solve solver 1 in out out.close() out.close out String[] args args static class A {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            long x = in.nextLong();
            out.print(getString(x));
        }

        private static String getString(long n) {
            char[] buf = new char[(int) StrictMath.floor(StrictMath.log(25 * (n + 1)) / StrictMath.log(26))];
            for (int i = buf.length - 1; i >= 0; i--) {
                n--;
                buf[i] = (char) ('a' + n % 26);
                n /= 26;
            }
            return new String(buf);
        }

    } A public void solve(int testNumber, Scanner in, PrintWriter out) {
            long x = in.nextLong();
            out.print(getString(x));
        } solve {
            long x = in.nextLong();
            out.print(getString(x));
        } long x = in.nextLong(); x in.nextLong() in.nextLong in out.print(getString(x)) out.print out getString(x) getString x int testNumber testNumber Scanner in in PrintWriter out out private static String getString(long n) {
            char[] buf = new char[(int) StrictMath.floor(StrictMath.log(25 * (n + 1)) / StrictMath.log(26))];
            for (int i = buf.length - 1; i >= 0; i--) {
                n--;
                buf[i] = (char) ('a' + n % 26);
                n /= 26;
            }
            return new String(buf);
        } getString {
            char[] buf = new char[(int) StrictMath.floor(StrictMath.log(25 * (n + 1)) / StrictMath.log(26))];
            for (int i = buf.length - 1; i >= 0; i--) {
                n--;
                buf[i] = (char) ('a' + n % 26);
                n /= 26;
            }
            return new String(buf);
        } char[] buf = new char[(int) StrictMath.floor(StrictMath.log(25 * (n + 1)) / StrictMath.log(26))]; buf new char[(int) StrictMath.floor(StrictMath.log(25 * (n + 1)) / StrictMath.log(26))] (int) StrictMath.floor(StrictMath.log(25 * (n + 1)) / StrictMath.log(26)) StrictMath.floor StrictMath StrictMath.log(25 * (n + 1)) / StrictMath.log(26) StrictMath.log(25 * (n + 1)) StrictMath.log StrictMath 25 * (n + 1) 25 (n + 1) n 1 StrictMath.log(26) StrictMath.log StrictMath 26 for (int i = buf.length - 1; i >= 0; i--) {
                n--;
                buf[i] = (char) ('a' + n % 26);
                n /= 26;
            } int i = buf.length - 1; int i = buf.length - 1; i buf.length - 1 buf.length buf buf.length 1 i >= 0 i 0 i-- i-- i {
                n--;
                buf[i] = (char) ('a' + n % 26);
                n /= 26;
            } {
                n--;
                buf[i] = (char) ('a' + n % 26);
                n /= 26;
            } n-- n buf[i] = (char) ('a' + n % 26) buf[i] buf i (char) ('a' + n % 26) 'a' n % 26 n 26 n /= 26 n 26 return new String(buf); new String(buf) long n n public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        A solver = new A();
        solver.solve(1, in, out);
        out.close();
    }

    static class A {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            long x = in.nextLong();
            out.print(getString(x));
        }

        private static String getString(long n) {
            char[] buf = new char[(int) StrictMath.floor(StrictMath.log(25 * (n + 1)) / StrictMath.log(26))];
            for (int i = buf.length - 1; i >= 0; i--) {
                n--;
                buf[i] = (char) ('a' + n % 26);
                n /= 26;
            }
            return new String(buf);
        }

    }
} public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        A solver = new A();
        solver.solve(1, in, out);
        out.close();
    }

    static class A {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            long x = in.nextLong();
            out.print(getString(x));
        }

        private static String getString(long n) {
            char[] buf = new char[(int) StrictMath.floor(StrictMath.log(25 * (n + 1)) / StrictMath.log(26))];
            for (int i = buf.length - 1; i >= 0; i--) {
                n--;
                buf[i] = (char) ('a' + n % 26);
                n /= 26;
            }
            return new String(buf);
        }

    }
} Main
import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Scanner;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author Ahmad Hamadneh
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        A solver = new A();
        solver.solve(1, in, out);
        out.close();
    }

    static class A {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            long x = in.nextLong();
            out.print(getString(x));
        }

        private static String getString(long n) {
            char[] buf = new char[(int) StrictMath.floor(StrictMath.log(25 * (n + 1)) / StrictMath.log(26))];
            for (int i = buf.length - 1; i >= 0; i--) {
                n--;
                buf[i] = (char) ('a' + n % 26);
                n /= 26;
            }
            return new String(buf);
        }

    }
}

