
import java.text.DecimalFormat;
import java.util.stream.LongStream;
import java.util.stream.IntStream;
import java.io.*;
import java.util.*;

public class Main {

    public static void main(String[] args) {
        FastScanner sc = new FastScanner();
        PrintWriter out = new PrintWriter(System.out);

        AtCoder problem = new AtCoder(sc);
        problem.solve(out);

        out.flush();
    }

}

class AtCoder {

    long N;

    AtCoder(FastScanner sc) {
        N = sc.nextLong();
    }

    void solve(PrintWriter out) {
        List<Character> ls = new ArrayList<>();
        ls.add('z');
        for (char c = 'a'; c <= 'z'; c++) {
            ls.add(c);
        }
        String ans = "";
        while (N > 0) {
            int rem = (int) (N % 26);
            ans += ls.get(rem);
            N--;
            N /= 26;
        }
        out.println(My.reverse(ans));
    }

}

class FastScanner {

    private final InputStream in = System.in;
    private final byte[] buffer = new byte[1024];
    private int ptr = 0;
    private int buflen = 0;

    private boolean hasNextByte() {
        if (ptr < buflen) {
            return true;
        } else {
            ptr = 0;
            try {
                buflen = in.read(buffer);
            } catch (IOException e) {
                e.printStackTrace();
            }
            if (buflen <= 0) {
                return false;
            }
        }
        return true;
    }

    private int readByte() {
        if (hasNextByte()) {
            return buffer[ptr++];
        } else {
            return -1;
        }
    }

    private static boolean isPrintableChar(int c) {
        return 33 <= c && c <= 126;
    }

    public boolean hasNext() {
        while (hasNextByte() && !isPrintableChar(buffer[ptr])) {
            ptr++;
        }
        return hasNextByte();
    }

    public String next() {
        if (!hasNext()) {
            throw new NoSuchElementException();
        }
        StringBuilder sb = new StringBuilder();
        int b = readByte();
        while (isPrintableChar(b)) {
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    }

    public long nextLong() {
        if (!hasNext()) {
            throw new NoSuchElementException();
        }
        long n = 0;
        boolean minus = false;
        int b = readByte();
        if (b == '-') {
            minus = true;
            b = readByte();
        }
        if (b < '0' || '9' < b) {
            throw new NumberFormatException();
        }
        while (true) {
            if ('0' <= b && b <= '9') {
                n *= 10;
                n += b - '0';
            } else if (b == -1 || !isPrintableChar(b)) {
                return minus ? -n : n;
            } else {
                throw new NumberFormatException();
            }
            b = readByte();
        }
    }

    public int nextInt() {
        long nl = nextLong();
        if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE) {
            throw new NumberFormatException();
        }
        return (int) nl;
    }

    public double nextDouble() {
        return Double.parseDouble(next());
    }

    public int[] arrayInt(int N) {
        int[] array = new int[N];
        for (int i = 0; i < N; i++) {
            array[i] = nextInt();
        }
        return array;
    }

    public long[] arrayLong(int N) {
        long[] array = new long[N];
        for (int i = 0; i < N; i++) {
            array[i] = nextLong();
        }
        return array;
    }

    public double[] arrayDouble(int N) {
        double[] array = new double[N];
        for (int i = 0; i < N; i++) {
            array[i] = nextDouble();
        }
        return array;
    }

    public String[] arrayString(int N) {
        String[] array = new String[N];
        for (int i = 0; i < N; i++) {
            array[i] = next();
        }
        return array;
    }
}

class My {

    static void ans(boolean b) {
        System.out.println(b ? "Yes" : "No");
    }

    static void ANS(boolean b) {
        System.out.println(b ? "YES" : "NO");
    }

    static String sort(String s) {
        char[] ch = s.toCharArray();
        Arrays.sort(ch);
        return String.valueOf(ch);
    }

    static String reverse(String s) {
        return new StringBuilder(s).reverse().toString();
    }

    static int[] reverse(int[] array) {
        for (int i = 0; i < array.length / 2; i++) {
            int temp = array[i];
            array[i] = array[array.length - 1 - i];
            array[array.length - 1 - i] = temp;
        }
        return array;
    }

    static long[] reverse(long[] array) {
        for (int i = 0; i < array.length / 2; i++) {
            long temp = array[i];
            array[i] = array[array.length - 1 - i];
            array[array.length - 1 - i] = temp;
        }
        return array;
    }

    static double[] reverse(double[] array) {
        for (int i = 0; i < array.length / 2; i++) {
            double temp = array[i];
            array[i] = array[array.length - 1 - i];
            array[array.length - 1 - i] = temp;
        }
        return array;
    }

    static String[] reverse(String[] array) {
        for (int i = 0; i < array.length / 2; i++) {
            String temp = array[i];
            array[i] = array[array.length - 1 - i];
            array[array.length - 1 - i] = temp;
        }
        return array;
    }

    static char[] reverse(char[] array) {
        for (int i = 0; i < array.length / 2; i++) {
            char temp = array[i];
            array[i] = array[array.length - 1 - i];
            array[array.length - 1 - i] = temp;
        }
        return array;
    }

    static long min(long... numbers) {
        Arrays.sort(numbers);
        return numbers[0];
    }

    static int min(int... numbers) {
        Arrays.sort(numbers);
        return numbers[0];
    }

    static double min(double... numbers) {
        Arrays.sort(numbers);
        return numbers[0];
    }

    static long max(long... numbers) {
        Arrays.sort(numbers);
        return numbers[numbers.length - 1];
    }

    static int max(int... numbers) {
        Arrays.sort(numbers);
        return numbers[numbers.length - 1];
    }

    static double max(double... numbers) {
        Arrays.sort(numbers);
        return numbers[numbers.length - 1];
    }

    static int sum(long number) {
        int sum = 0;
        while (number > 0) {
            sum += number % 10;
            number /= 10;
        }
        return sum;
    }

} import java.text.DecimalFormat; DecimalFormat java.text import java.util.stream.LongStream; LongStream java.util.stream import java.util.stream.IntStream; IntStream java.util.stream import java.io.*; io.* java import java.util.*; util.* java public class Main {

    public static void main(String[] args) {
        FastScanner sc = new FastScanner();
        PrintWriter out = new PrintWriter(System.out);

        AtCoder problem = new AtCoder(sc);
        problem.solve(out);

        out.flush();
    }

} Main public static void main(String[] args) {
        FastScanner sc = new FastScanner();
        PrintWriter out = new PrintWriter(System.out);

        AtCoder problem = new AtCoder(sc);
        problem.solve(out);

        out.flush();
    } main {
        FastScanner sc = new FastScanner();
        PrintWriter out = new PrintWriter(System.out);

        AtCoder problem = new AtCoder(sc);
        problem.solve(out);

        out.flush();
    } FastScanner sc = new FastScanner(); sc new FastScanner() PrintWriter out = new PrintWriter(System.out); out new PrintWriter(System.out) AtCoder problem = new AtCoder(sc); problem new AtCoder(sc) problem.solve(out) problem.solve problem out out.flush() out.flush out String[] args args class AtCoder {

    long N;

    AtCoder(FastScanner sc) {
        N = sc.nextLong();
    }

    void solve(PrintWriter out) {
        List<Character> ls = new ArrayList<>();
        ls.add('z');
        for (char c = 'a'; c <= 'z'; c++) {
            ls.add(c);
        }
        String ans = "";
        while (N > 0) {
            int rem = (int) (N % 26);
            ans += ls.get(rem);
            N--;
            N /= 26;
        }
        out.println(My.reverse(ans));
    }

} AtCoder long N; N AtCoder(FastScanner sc) {
        N = sc.nextLong();
    } AtCoder {
        N = sc.nextLong();
    } N = sc.nextLong() N sc.nextLong() sc.nextLong sc FastScanner sc sc void solve(PrintWriter out) {
        List<Character> ls = new ArrayList<>();
        ls.add('z');
        for (char c = 'a'; c <= 'z'; c++) {
            ls.add(c);
        }
        String ans = "";
        while (N > 0) {
            int rem = (int) (N % 26);
            ans += ls.get(rem);
            N--;
            N /= 26;
        }
        out.println(My.reverse(ans));
    } solve {
        List<Character> ls = new ArrayList<>();
        ls.add('z');
        for (char c = 'a'; c <= 'z'; c++) {
            ls.add(c);
        }
        String ans = "";
        while (N > 0) {
            int rem = (int) (N % 26);
            ans += ls.get(rem);
            N--;
            N /= 26;
        }
        out.println(My.reverse(ans));
    } List<Character> ls = new ArrayList<>(); ls new ArrayList<>() ls.add('z') ls.add ls 'z' for (char c = 'a'; c <= 'z'; c++) {
            ls.add(c);
        } char c = 'a'; char c = 'a'; c 'a' c <= 'z' c 'z' c++ c++ c {
            ls.add(c);
        } {
            ls.add(c);
        } ls.add(c) ls.add ls c String ans = ""; ans "" while (N > 0) {
            int rem = (int) (N % 26);
            ans += ls.get(rem);
            N--;
            N /= 26;
        } N > 0 N 0 {
            int rem = (int) (N % 26);
            ans += ls.get(rem);
            N--;
            N /= 26;
        } int rem = (int) (N % 26); rem (int) (N % 26) N 26 ans += ls.get(rem) ans ls.get(rem) ls.get ls rem N-- N N /= 26 N 26 out.println(My.reverse(ans)) out.println out My.reverse(ans) My.reverse My ans PrintWriter out out class FastScanner {

    private final InputStream in = System.in;
    private final byte[] buffer = new byte[1024];
    private int ptr = 0;
    private int buflen = 0;

    private boolean hasNextByte() {
        if (ptr < buflen) {
            return true;
        } else {
            ptr = 0;
            try {
                buflen = in.read(buffer);
            } catch (IOException e) {
                e.printStackTrace();
            }
            if (buflen <= 0) {
                return false;
            }
        }
        return true;
    }

    private int readByte() {
        if (hasNextByte()) {
            return buffer[ptr++];
        } else {
            return -1;
        }
    }

    private static boolean isPrintableChar(int c) {
        return 33 <= c && c <= 126;
    }

    public boolean hasNext() {
        while (hasNextByte() && !isPrintableChar(buffer[ptr])) {
            ptr++;
        }
        return hasNextByte();
    }

    public String next() {
        if (!hasNext()) {
            throw new NoSuchElementException();
        }
        StringBuilder sb = new StringBuilder();
        int b = readByte();
        while (isPrintableChar(b)) {
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    }

    public long nextLong() {
        if (!hasNext()) {
            throw new NoSuchElementException();
        }
        long n = 0;
        boolean minus = false;
        int b = readByte();
        if (b == '-') {
            minus = true;
            b = readByte();
        }
        if (b < '0' || '9' < b) {
            throw new NumberFormatException();
        }
        while (true) {
            if ('0' <= b && b <= '9') {
                n *= 10;
                n += b - '0';
            } else if (b == -1 || !isPrintableChar(b)) {
                return minus ? -n : n;
            } else {
                throw new NumberFormatException();
            }
            b = readByte();
        }
    }

    public int nextInt() {
        long nl = nextLong();
        if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE) {
            throw new NumberFormatException();
        }
        return (int) nl;
    }

    public double nextDouble() {
        return Double.parseDouble(next());
    }

    public int[] arrayInt(int N) {
        int[] array = new int[N];
        for (int i = 0; i < N; i++) {
            array[i] = nextInt();
        }
        return array;
    }

    public long[] arrayLong(int N) {
        long[] array = new long[N];
        for (int i = 0; i < N; i++) {
            array[i] = nextLong();
        }
        return array;
    }

    public double[] arrayDouble(int N) {
        double[] array = new double[N];
        for (int i = 0; i < N; i++) {
            array[i] = nextDouble();
        }
        return array;
    }

    public String[] arrayString(int N) {
        String[] array = new String[N];
        for (int i = 0; i < N; i++) {
            array[i] = next();
        }
        return array;
    }
} FastScanner private final InputStream in = System.in; in System.in System System.in private final byte[] buffer = new byte[1024]; buffer new byte[1024] 1024 private int ptr = 0; ptr 0 private int buflen = 0; buflen 0 private boolean hasNextByte() {
        if (ptr < buflen) {
            return true;
        } else {
            ptr = 0;
            try {
                buflen = in.read(buffer);
            } catch (IOException e) {
                e.printStackTrace();
            }
            if (buflen <= 0) {
                return false;
            }
        }
        return true;
    } hasNextByte {
        if (ptr < buflen) {
            return true;
        } else {
            ptr = 0;
            try {
                buflen = in.read(buffer);
            } catch (IOException e) {
                e.printStackTrace();
            }
            if (buflen <= 0) {
                return false;
            }
        }
        return true;
    } if (ptr < buflen) {
            return true;
        } else {
            ptr = 0;
            try {
                buflen = in.read(buffer);
            } catch (IOException e) {
                e.printStackTrace();
            }
            if (buflen <= 0) {
                return false;
            }
        } ptr < buflen ptr buflen {
            return true;
        } return true; true {
            ptr = 0;
            try {
                buflen = in.read(buffer);
            } catch (IOException e) {
                e.printStackTrace();
            }
            if (buflen <= 0) {
                return false;
            }
        } ptr = 0 ptr 0 try {
                buflen = in.read(buffer);
            } catch (IOException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            } IOException e {
                e.printStackTrace();
            } e.printStackTrace() e.printStackTrace e {
                buflen = in.read(buffer);
            } buflen = in.read(buffer) buflen in.read(buffer) in.read in buffer if (buflen <= 0) {
                return false;
            } buflen <= 0 buflen 0 {
                return false;
            } return false; false return true; true private int readByte() {
        if (hasNextByte()) {
            return buffer[ptr++];
        } else {
            return -1;
        }
    } readByte {
        if (hasNextByte()) {
            return buffer[ptr++];
        } else {
            return -1;
        }
    } if (hasNextByte()) {
            return buffer[ptr++];
        } else {
            return -1;
        } hasNextByte() hasNextByte {
            return buffer[ptr++];
        } return buffer[ptr++]; buffer[ptr++] buffer ptr++ ptr {
            return -1;
        } return -1; -1 1 private static boolean isPrintableChar(int c) {
        return 33 <= c && c <= 126;
    } isPrintableChar {
        return 33 <= c && c <= 126;
    } return 33 <= c && c <= 126; 33 <= c && c <= 126 33 <= c 33 c c <= 126 c 126 int c c public boolean hasNext() {
        while (hasNextByte() && !isPrintableChar(buffer[ptr])) {
            ptr++;
        }
        return hasNextByte();
    } hasNext {
        while (hasNextByte() && !isPrintableChar(buffer[ptr])) {
            ptr++;
        }
        return hasNextByte();
    } while (hasNextByte() && !isPrintableChar(buffer[ptr])) {
            ptr++;
        } hasNextByte() && !isPrintableChar(buffer[ptr]) hasNextByte() hasNextByte !isPrintableChar(buffer[ptr]) isPrintableChar(buffer[ptr]) isPrintableChar buffer[ptr] buffer ptr {
            ptr++;
        } ptr++ ptr return hasNextByte(); hasNextByte() hasNextByte public String next() {
        if (!hasNext()) {
            throw new NoSuchElementException();
        }
        StringBuilder sb = new StringBuilder();
        int b = readByte();
        while (isPrintableChar(b)) {
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    } next {
        if (!hasNext()) {
            throw new NoSuchElementException();
        }
        StringBuilder sb = new StringBuilder();
        int b = readByte();
        while (isPrintableChar(b)) {
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    } if (!hasNext()) {
            throw new NoSuchElementException();
        } !hasNext() hasNext() hasNext {
            throw new NoSuchElementException();
        } throw new NoSuchElementException(); new NoSuchElementException() StringBuilder sb = new StringBuilder(); sb new StringBuilder() int b = readByte(); b readByte() readByte while (isPrintableChar(b)) {
            sb.appendCodePoint(b);
            b = readByte();
        } isPrintableChar(b) isPrintableChar b {
            sb.appendCodePoint(b);
            b = readByte();
        } sb.appendCodePoint(b) sb.appendCodePoint sb b b = readByte() b readByte() readByte return sb.toString(); sb.toString() sb.toString sb public long nextLong() {
        if (!hasNext()) {
            throw new NoSuchElementException();
        }
        long n = 0;
        boolean minus = false;
        int b = readByte();
        if (b == '-') {
            minus = true;
            b = readByte();
        }
        if (b < '0' || '9' < b) {
            throw new NumberFormatException();
        }
        while (true) {
            if ('0' <= b && b <= '9') {
                n *= 10;
                n += b - '0';
            } else if (b == -1 || !isPrintableChar(b)) {
                return minus ? -n : n;
            } else {
                throw new NumberFormatException();
            }
            b = readByte();
        }
    } nextLong {
        if (!hasNext()) {
            throw new NoSuchElementException();
        }
        long n = 0;
        boolean minus = false;
        int b = readByte();
        if (b == '-') {
            minus = true;
            b = readByte();
        }
        if (b < '0' || '9' < b) {
            throw new NumberFormatException();
        }
        while (true) {
            if ('0' <= b && b <= '9') {
                n *= 10;
                n += b - '0';
            } else if (b == -1 || !isPrintableChar(b)) {
                return minus ? -n : n;
            } else {
                throw new NumberFormatException();
            }
            b = readByte();
        }
    } if (!hasNext()) {
            throw new NoSuchElementException();
        } !hasNext() hasNext() hasNext {
            throw new NoSuchElementException();
        } throw new NoSuchElementException(); new NoSuchElementException() long n = 0; n 0 boolean minus = false; minus false int b = readByte(); b readByte() readByte if (b == '-') {
            minus = true;
            b = readByte();
        } b == '-' b '-' {
            minus = true;
            b = readByte();
        } minus = true minus true b = readByte() b readByte() readByte if (b < '0' || '9' < b) {
            throw new NumberFormatException();
        } b < '0' || '9' < b b < '0' b '0' '9' < b '9' b {
            throw new NumberFormatException();
        } throw new NumberFormatException(); new NumberFormatException() while (true) {
            if ('0' <= b && b <= '9') {
                n *= 10;
                n += b - '0';
            } else if (b == -1 || !isPrintableChar(b)) {
                return minus ? -n : n;
            } else {
                throw new NumberFormatException();
            }
            b = readByte();
        } true {
            if ('0' <= b && b <= '9') {
                n *= 10;
                n += b - '0';
            } else if (b == -1 || !isPrintableChar(b)) {
                return minus ? -n : n;
            } else {
                throw new NumberFormatException();
            }
            b = readByte();
        } if ('0' <= b && b <= '9') {
                n *= 10;
                n += b - '0';
            } else if (b == -1 || !isPrintableChar(b)) {
                return minus ? -n : n;
            } else {
                throw new NumberFormatException();
            } '0' <= b && b <= '9' '0' <= b '0' b b <= '9' b '9' {
                n *= 10;
                n += b - '0';
            } n *= 10 n 10 n += b - '0' n b - '0' b '0' if (b == -1 || !isPrintableChar(b)) {
                return minus ? -n : n;
            } else {
                throw new NumberFormatException();
            } b == -1 || !isPrintableChar(b) b == -1 b -1 1 !isPrintableChar(b) isPrintableChar(b) isPrintableChar b {
                return minus ? -n : n;
            } return minus ? -n : n; minus ? -n : n minus -n n n {
                throw new NumberFormatException();
            } throw new NumberFormatException(); new NumberFormatException() b = readByte() b readByte() readByte public int nextInt() {
        long nl = nextLong();
        if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE) {
            throw new NumberFormatException();
        }
        return (int) nl;
    } nextInt {
        long nl = nextLong();
        if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE) {
            throw new NumberFormatException();
        }
        return (int) nl;
    } long nl = nextLong(); nl nextLong() nextLong if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE) {
            throw new NumberFormatException();
        } nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE nl < Integer.MIN_VALUE nl Integer.MIN_VALUE Integer Integer.MIN_VALUE nl > Integer.MAX_VALUE nl Integer.MAX_VALUE Integer Integer.MAX_VALUE {
            throw new NumberFormatException();
        } throw new NumberFormatException(); new NumberFormatException() return (int) nl; (int) nl public double nextDouble() {
        return Double.parseDouble(next());
    } nextDouble {
        return Double.parseDouble(next());
    } return Double.parseDouble(next()); Double.parseDouble(next()) Double.parseDouble Double next() next public int[] arrayInt(int N) {
        int[] array = new int[N];
        for (int i = 0; i < N; i++) {
            array[i] = nextInt();
        }
        return array;
    } arrayInt {
        int[] array = new int[N];
        for (int i = 0; i < N; i++) {
            array[i] = nextInt();
        }
        return array;
    } int[] array = new int[N]; array new int[N] N for (int i = 0; i < N; i++) {
            array[i] = nextInt();
        } int i = 0; int i = 0; i 0 i < N i N i++ i++ i {
            array[i] = nextInt();
        } {
            array[i] = nextInt();
        } array[i] = nextInt() array[i] array i nextInt() nextInt return array; array int N N public long[] arrayLong(int N) {
        long[] array = new long[N];
        for (int i = 0; i < N; i++) {
            array[i] = nextLong();
        }
        return array;
    } arrayLong {
        long[] array = new long[N];
        for (int i = 0; i < N; i++) {
            array[i] = nextLong();
        }
        return array;
    } long[] array = new long[N]; array new long[N] N for (int i = 0; i < N; i++) {
            array[i] = nextLong();
        } int i = 0; int i = 0; i 0 i < N i N i++ i++ i {
            array[i] = nextLong();
        } {
            array[i] = nextLong();
        } array[i] = nextLong() array[i] array i nextLong() nextLong return array; array int N N public double[] arrayDouble(int N) {
        double[] array = new double[N];
        for (int i = 0; i < N; i++) {
            array[i] = nextDouble();
        }
        return array;
    } arrayDouble {
        double[] array = new double[N];
        for (int i = 0; i < N; i++) {
            array[i] = nextDouble();
        }
        return array;
    } double[] array = new double[N]; array new double[N] N for (int i = 0; i < N; i++) {
            array[i] = nextDouble();
        } int i = 0; int i = 0; i 0 i < N i N i++ i++ i {
            array[i] = nextDouble();
        } {
            array[i] = nextDouble();
        } array[i] = nextDouble() array[i] array i nextDouble() nextDouble return array; array int N N public String[] arrayString(int N) {
        String[] array = new String[N];
        for (int i = 0; i < N; i++) {
            array[i] = next();
        }
        return array;
    } arrayString {
        String[] array = new String[N];
        for (int i = 0; i < N; i++) {
            array[i] = next();
        }
        return array;
    } String[] array = new String[N]; array new String[N] N for (int i = 0; i < N; i++) {
            array[i] = next();
        } int i = 0; int i = 0; i 0 i < N i N i++ i++ i {
            array[i] = next();
        } {
            array[i] = next();
        } array[i] = next() array[i] array i next() next return array; array int N N class My {

    static void ans(boolean b) {
        System.out.println(b ? "Yes" : "No");
    }

    static void ANS(boolean b) {
        System.out.println(b ? "YES" : "NO");
    }

    static String sort(String s) {
        char[] ch = s.toCharArray();
        Arrays.sort(ch);
        return String.valueOf(ch);
    }

    static String reverse(String s) {
        return new StringBuilder(s).reverse().toString();
    }

    static int[] reverse(int[] array) {
        for (int i = 0; i < array.length / 2; i++) {
            int temp = array[i];
            array[i] = array[array.length - 1 - i];
            array[array.length - 1 - i] = temp;
        }
        return array;
    }

    static long[] reverse(long[] array) {
        for (int i = 0; i < array.length / 2; i++) {
            long temp = array[i];
            array[i] = array[array.length - 1 - i];
            array[array.length - 1 - i] = temp;
        }
        return array;
    }

    static double[] reverse(double[] array) {
        for (int i = 0; i < array.length / 2; i++) {
            double temp = array[i];
            array[i] = array[array.length - 1 - i];
            array[array.length - 1 - i] = temp;
        }
        return array;
    }

    static String[] reverse(String[] array) {
        for (int i = 0; i < array.length / 2; i++) {
            String temp = array[i];
            array[i] = array[array.length - 1 - i];
            array[array.length - 1 - i] = temp;
        }
        return array;
    }

    static char[] reverse(char[] array) {
        for (int i = 0; i < array.length / 2; i++) {
            char temp = array[i];
            array[i] = array[array.length - 1 - i];
            array[array.length - 1 - i] = temp;
        }
        return array;
    }

    static long min(long... numbers) {
        Arrays.sort(numbers);
        return numbers[0];
    }

    static int min(int... numbers) {
        Arrays.sort(numbers);
        return numbers[0];
    }

    static double min(double... numbers) {
        Arrays.sort(numbers);
        return numbers[0];
    }

    static long max(long... numbers) {
        Arrays.sort(numbers);
        return numbers[numbers.length - 1];
    }

    static int max(int... numbers) {
        Arrays.sort(numbers);
        return numbers[numbers.length - 1];
    }

    static double max(double... numbers) {
        Arrays.sort(numbers);
        return numbers[numbers.length - 1];
    }

    static int sum(long number) {
        int sum = 0;
        while (number > 0) {
            sum += number % 10;
            number /= 10;
        }
        return sum;
    }

} My static void ans(boolean b) {
        System.out.println(b ? "Yes" : "No");
    } ans {
        System.out.println(b ? "Yes" : "No");
    } System.out.println(b ? "Yes" : "No") System.out.println System.out System System.out b ? "Yes" : "No" b "Yes" "No" boolean b b static void ANS(boolean b) {
        System.out.println(b ? "YES" : "NO");
    } ANS {
        System.out.println(b ? "YES" : "NO");
    } System.out.println(b ? "YES" : "NO") System.out.println System.out System System.out b ? "YES" : "NO" b "YES" "NO" boolean b b static String sort(String s) {
        char[] ch = s.toCharArray();
        Arrays.sort(ch);
        return String.valueOf(ch);
    } sort {
        char[] ch = s.toCharArray();
        Arrays.sort(ch);
        return String.valueOf(ch);
    } char[] ch = s.toCharArray(); ch s.toCharArray() s.toCharArray s Arrays.sort(ch) Arrays.sort Arrays ch return String.valueOf(ch); String.valueOf(ch) String.valueOf String ch String s s static String reverse(String s) {
        return new StringBuilder(s).reverse().toString();
    } reverse {
        return new StringBuilder(s).reverse().toString();
    } return new StringBuilder(s).reverse().toString(); new StringBuilder(s).reverse().toString() new StringBuilder(s).reverse().toString new StringBuilder(s).reverse() new StringBuilder(s).reverse new StringBuilder(s) String s s static int[] reverse(int[] array) {
        for (int i = 0; i < array.length / 2; i++) {
            int temp = array[i];
            array[i] = array[array.length - 1 - i];
            array[array.length - 1 - i] = temp;
        }
        return array;
    } reverse {
        for (int i = 0; i < array.length / 2; i++) {
            int temp = array[i];
            array[i] = array[array.length - 1 - i];
            array[array.length - 1 - i] = temp;
        }
        return array;
    } for (int i = 0; i < array.length / 2; i++) {
            int temp = array[i];
            array[i] = array[array.length - 1 - i];
            array[array.length - 1 - i] = temp;
        } int i = 0; int i = 0; i 0 i < array.length / 2 i array.length / 2 array.length array array.length 2 i++ i++ i {
            int temp = array[i];
            array[i] = array[array.length - 1 - i];
            array[array.length - 1 - i] = temp;
        } {
            int temp = array[i];
            array[i] = array[array.length - 1 - i];
            array[array.length - 1 - i] = temp;
        } int temp = array[i]; temp array[i] array i array[i] = array[array.length - 1 - i] array[i] array i array[array.length - 1 - i] array array.length - 1 - i array.length - 1 - i array.length array array.length 1 i array[array.length - 1 - i] = temp array[array.length - 1 - i] array array.length - 1 - i array.length - 1 - i array.length array array.length 1 i temp return array; array int[] array array static long[] reverse(long[] array) {
        for (int i = 0; i < array.length / 2; i++) {
            long temp = array[i];
            array[i] = array[array.length - 1 - i];
            array[array.length - 1 - i] = temp;
        }
        return array;
    } reverse {
        for (int i = 0; i < array.length / 2; i++) {
            long temp = array[i];
            array[i] = array[array.length - 1 - i];
            array[array.length - 1 - i] = temp;
        }
        return array;
    } for (int i = 0; i < array.length / 2; i++) {
            long temp = array[i];
            array[i] = array[array.length - 1 - i];
            array[array.length - 1 - i] = temp;
        } int i = 0; int i = 0; i 0 i < array.length / 2 i array.length / 2 array.length array array.length 2 i++ i++ i {
            long temp = array[i];
            array[i] = array[array.length - 1 - i];
            array[array.length - 1 - i] = temp;
        } {
            long temp = array[i];
            array[i] = array[array.length - 1 - i];
            array[array.length - 1 - i] = temp;
        } long temp = array[i]; temp array[i] array i array[i] = array[array.length - 1 - i] array[i] array i array[array.length - 1 - i] array array.length - 1 - i array.length - 1 - i array.length array array.length 1 i array[array.length - 1 - i] = temp array[array.length - 1 - i] array array.length - 1 - i array.length - 1 - i array.length array array.length 1 i temp return array; array long[] array array static double[] reverse(double[] array) {
        for (int i = 0; i < array.length / 2; i++) {
            double temp = array[i];
            array[i] = array[array.length - 1 - i];
            array[array.length - 1 - i] = temp;
        }
        return array;
    } reverse {
        for (int i = 0; i < array.length / 2; i++) {
            double temp = array[i];
            array[i] = array[array.length - 1 - i];
            array[array.length - 1 - i] = temp;
        }
        return array;
    } for (int i = 0; i < array.length / 2; i++) {
            double temp = array[i];
            array[i] = array[array.length - 1 - i];
            array[array.length - 1 - i] = temp;
        } int i = 0; int i = 0; i 0 i < array.length / 2 i array.length / 2 array.length array array.length 2 i++ i++ i {
            double temp = array[i];
            array[i] = array[array.length - 1 - i];
            array[array.length - 1 - i] = temp;
        } {
            double temp = array[i];
            array[i] = array[array.length - 1 - i];
            array[array.length - 1 - i] = temp;
        } double temp = array[i]; temp array[i] array i array[i] = array[array.length - 1 - i] array[i] array i array[array.length - 1 - i] array array.length - 1 - i array.length - 1 - i array.length array array.length 1 i array[array.length - 1 - i] = temp array[array.length - 1 - i] array array.length - 1 - i array.length - 1 - i array.length array array.length 1 i temp return array; array double[] array array static String[] reverse(String[] array) {
        for (int i = 0; i < array.length / 2; i++) {
            String temp = array[i];
            array[i] = array[array.length - 1 - i];
            array[array.length - 1 - i] = temp;
        }
        return array;
    } reverse {
        for (int i = 0; i < array.length / 2; i++) {
            String temp = array[i];
            array[i] = array[array.length - 1 - i];
            array[array.length - 1 - i] = temp;
        }
        return array;
    } for (int i = 0; i < array.length / 2; i++) {
            String temp = array[i];
            array[i] = array[array.length - 1 - i];
            array[array.length - 1 - i] = temp;
        } int i = 0; int i = 0; i 0 i < array.length / 2 i array.length / 2 array.length array array.length 2 i++ i++ i {
            String temp = array[i];
            array[i] = array[array.length - 1 - i];
            array[array.length - 1 - i] = temp;
        } {
            String temp = array[i];
            array[i] = array[array.length - 1 - i];
            array[array.length - 1 - i] = temp;
        } String temp = array[i]; temp array[i] array i array[i] = array[array.length - 1 - i] array[i] array i array[array.length - 1 - i] array array.length - 1 - i array.length - 1 - i array.length array array.length 1 i array[array.length - 1 - i] = temp array[array.length - 1 - i] array array.length - 1 - i array.length - 1 - i array.length array array.length 1 i temp return array; array String[] array array static char[] reverse(char[] array) {
        for (int i = 0; i < array.length / 2; i++) {
            char temp = array[i];
            array[i] = array[array.length - 1 - i];
            array[array.length - 1 - i] = temp;
        }
        return array;
    } reverse {
        for (int i = 0; i < array.length / 2; i++) {
            char temp = array[i];
            array[i] = array[array.length - 1 - i];
            array[array.length - 1 - i] = temp;
        }
        return array;
    } for (int i = 0; i < array.length / 2; i++) {
            char temp = array[i];
            array[i] = array[array.length - 1 - i];
            array[array.length - 1 - i] = temp;
        } int i = 0; int i = 0; i 0 i < array.length / 2 i array.length / 2 array.length array array.length 2 i++ i++ i {
            char temp = array[i];
            array[i] = array[array.length - 1 - i];
            array[array.length - 1 - i] = temp;
        } {
            char temp = array[i];
            array[i] = array[array.length - 1 - i];
            array[array.length - 1 - i] = temp;
        } char temp = array[i]; temp array[i] array i array[i] = array[array.length - 1 - i] array[i] array i array[array.length - 1 - i] array array.length - 1 - i array.length - 1 - i array.length array array.length 1 i array[array.length - 1 - i] = temp array[array.length - 1 - i] array array.length - 1 - i array.length - 1 - i array.length array array.length 1 i temp return array; array char[] array array static long min(long... numbers) {
        Arrays.sort(numbers);
        return numbers[0];
    } min {
        Arrays.sort(numbers);
        return numbers[0];
    } Arrays.sort(numbers) Arrays.sort Arrays numbers return numbers[0]; numbers[0] numbers 0 long... numbers numbers static int min(int... numbers) {
        Arrays.sort(numbers);
        return numbers[0];
    } min {
        Arrays.sort(numbers);
        return numbers[0];
    } Arrays.sort(numbers) Arrays.sort Arrays numbers return numbers[0]; numbers[0] numbers 0 int... numbers numbers static double min(double... numbers) {
        Arrays.sort(numbers);
        return numbers[0];
    } min {
        Arrays.sort(numbers);
        return numbers[0];
    } Arrays.sort(numbers) Arrays.sort Arrays numbers return numbers[0]; numbers[0] numbers 0 double... numbers numbers static long max(long... numbers) {
        Arrays.sort(numbers);
        return numbers[numbers.length - 1];
    } max {
        Arrays.sort(numbers);
        return numbers[numbers.length - 1];
    } Arrays.sort(numbers) Arrays.sort Arrays numbers return numbers[numbers.length - 1]; numbers[numbers.length - 1] numbers numbers.length - 1 numbers.length numbers numbers.length 1 long... numbers numbers static int max(int... numbers) {
        Arrays.sort(numbers);
        return numbers[numbers.length - 1];
    } max {
        Arrays.sort(numbers);
        return numbers[numbers.length - 1];
    } Arrays.sort(numbers) Arrays.sort Arrays numbers return numbers[numbers.length - 1]; numbers[numbers.length - 1] numbers numbers.length - 1 numbers.length numbers numbers.length 1 int... numbers numbers static double max(double... numbers) {
        Arrays.sort(numbers);
        return numbers[numbers.length - 1];
    } max {
        Arrays.sort(numbers);
        return numbers[numbers.length - 1];
    } Arrays.sort(numbers) Arrays.sort Arrays numbers return numbers[numbers.length - 1]; numbers[numbers.length - 1] numbers numbers.length - 1 numbers.length numbers numbers.length 1 double... numbers numbers static int sum(long number) {
        int sum = 0;
        while (number > 0) {
            sum += number % 10;
            number /= 10;
        }
        return sum;
    } sum {
        int sum = 0;
        while (number > 0) {
            sum += number % 10;
            number /= 10;
        }
        return sum;
    } int sum = 0; sum 0 while (number > 0) {
            sum += number % 10;
            number /= 10;
        } number > 0 number 0 {
            sum += number % 10;
            number /= 10;
        } sum += number % 10 sum number % 10 number 10 number /= 10 number 10 return sum; sum long number number public class Main {

    public static void main(String[] args) {
        FastScanner sc = new FastScanner();
        PrintWriter out = new PrintWriter(System.out);

        AtCoder problem = new AtCoder(sc);
        problem.solve(out);

        out.flush();
    }

} public class Main {

    public static void main(String[] args) {
        FastScanner sc = new FastScanner();
        PrintWriter out = new PrintWriter(System.out);

        AtCoder problem = new AtCoder(sc);
        problem.solve(out);

        out.flush();
    }

} Main

import java.text.DecimalFormat;
import java.util.stream.LongStream;
import java.util.stream.IntStream;
import java.io.*;
import java.util.*;

public class Main {

    public static void main(String[] args) {
        FastScanner sc = new FastScanner();
        PrintWriter out = new PrintWriter(System.out);

        AtCoder problem = new AtCoder(sc);
        problem.solve(out);

        out.flush();
    }

}

class AtCoder {

    long N;

    AtCoder(FastScanner sc) {
        N = sc.nextLong();
    }

    void solve(PrintWriter out) {
        List<Character> ls = new ArrayList<>();
        ls.add('z');
        for (char c = 'a'; c <= 'z'; c++) {
            ls.add(c);
        }
        String ans = "";
        while (N > 0) {
            int rem = (int) (N % 26);
            ans += ls.get(rem);
            N--;
            N /= 26;
        }
        out.println(My.reverse(ans));
    }

}

class FastScanner {

    private final InputStream in = System.in;
    private final byte[] buffer = new byte[1024];
    private int ptr = 0;
    private int buflen = 0;

    private boolean hasNextByte() {
        if (ptr < buflen) {
            return true;
        } else {
            ptr = 0;
            try {
                buflen = in.read(buffer);
            } catch (IOException e) {
                e.printStackTrace();
            }
            if (buflen <= 0) {
                return false;
            }
        }
        return true;
    }

    private int readByte() {
        if (hasNextByte()) {
            return buffer[ptr++];
        } else {
            return -1;
        }
    }

    private static boolean isPrintableChar(int c) {
        return 33 <= c && c <= 126;
    }

    public boolean hasNext() {
        while (hasNextByte() && !isPrintableChar(buffer[ptr])) {
            ptr++;
        }
        return hasNextByte();
    }

    public String next() {
        if (!hasNext()) {
            throw new NoSuchElementException();
        }
        StringBuilder sb = new StringBuilder();
        int b = readByte();
        while (isPrintableChar(b)) {
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    }

    public long nextLong() {
        if (!hasNext()) {
            throw new NoSuchElementException();
        }
        long n = 0;
        boolean minus = false;
        int b = readByte();
        if (b == '-') {
            minus = true;
            b = readByte();
        }
        if (b < '0' || '9' < b) {
            throw new NumberFormatException();
        }
        while (true) {
            if ('0' <= b && b <= '9') {
                n *= 10;
                n += b - '0';
            } else if (b == -1 || !isPrintableChar(b)) {
                return minus ? -n : n;
            } else {
                throw new NumberFormatException();
            }
            b = readByte();
        }
    }

    public int nextInt() {
        long nl = nextLong();
        if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE) {
            throw new NumberFormatException();
        }
        return (int) nl;
    }

    public double nextDouble() {
        return Double.parseDouble(next());
    }

    public int[] arrayInt(int N) {
        int[] array = new int[N];
        for (int i = 0; i < N; i++) {
            array[i] = nextInt();
        }
        return array;
    }

    public long[] arrayLong(int N) {
        long[] array = new long[N];
        for (int i = 0; i < N; i++) {
            array[i] = nextLong();
        }
        return array;
    }

    public double[] arrayDouble(int N) {
        double[] array = new double[N];
        for (int i = 0; i < N; i++) {
            array[i] = nextDouble();
        }
        return array;
    }

    public String[] arrayString(int N) {
        String[] array = new String[N];
        for (int i = 0; i < N; i++) {
            array[i] = next();
        }
        return array;
    }
}

class My {

    static void ans(boolean b) {
        System.out.println(b ? "Yes" : "No");
    }

    static void ANS(boolean b) {
        System.out.println(b ? "YES" : "NO");
    }

    static String sort(String s) {
        char[] ch = s.toCharArray();
        Arrays.sort(ch);
        return String.valueOf(ch);
    }

    static String reverse(String s) {
        return new StringBuilder(s).reverse().toString();
    }

    static int[] reverse(int[] array) {
        for (int i = 0; i < array.length / 2; i++) {
            int temp = array[i];
            array[i] = array[array.length - 1 - i];
            array[array.length - 1 - i] = temp;
        }
        return array;
    }

    static long[] reverse(long[] array) {
        for (int i = 0; i < array.length / 2; i++) {
            long temp = array[i];
            array[i] = array[array.length - 1 - i];
            array[array.length - 1 - i] = temp;
        }
        return array;
    }

    static double[] reverse(double[] array) {
        for (int i = 0; i < array.length / 2; i++) {
            double temp = array[i];
            array[i] = array[array.length - 1 - i];
            array[array.length - 1 - i] = temp;
        }
        return array;
    }

    static String[] reverse(String[] array) {
        for (int i = 0; i < array.length / 2; i++) {
            String temp = array[i];
            array[i] = array[array.length - 1 - i];
            array[array.length - 1 - i] = temp;
        }
        return array;
    }

    static char[] reverse(char[] array) {
        for (int i = 0; i < array.length / 2; i++) {
            char temp = array[i];
            array[i] = array[array.length - 1 - i];
            array[array.length - 1 - i] = temp;
        }
        return array;
    }

    static long min(long... numbers) {
        Arrays.sort(numbers);
        return numbers[0];
    }

    static int min(int... numbers) {
        Arrays.sort(numbers);
        return numbers[0];
    }

    static double min(double... numbers) {
        Arrays.sort(numbers);
        return numbers[0];
    }

    static long max(long... numbers) {
        Arrays.sort(numbers);
        return numbers[numbers.length - 1];
    }

    static int max(int... numbers) {
        Arrays.sort(numbers);
        return numbers[numbers.length - 1];
    }

    static double max(double... numbers) {
        Arrays.sort(numbers);
        return numbers[numbers.length - 1];
    }

    static int sum(long number) {
        int sum = 0;
        while (number > 0) {
            sum += number % 10;
            number /= 10;
        }
        return sum;
    }

}
