Problem: You're given a list of n strings a1, a2, ..., an. You'd like to concatenate them together in some order such that the resulting string would be lexicographically smallest.

Given the list of strings, output the lexicographically smallest concatenation.

Input

The first line contains integer n — the number of strings (1 ≤ n ≤ 5·104).

Each of the next n lines contains one string ai (1 ≤ |ai| ≤ 50) consisting of only lowercase English letters. The sum of string lengths will not exceed 5·104.

Output

Print the only string a — the lexicographically smallest string concatenation.

Examples

Input

4
abba
abacaba
bcd
er


Output

abacabaabbabcder


Input

5
x
xx
xxa
xxaa
xxaaa


Output

xxaaaxxaaxxaxxx


Input

3
c
cb
cba


Output

cbacbc

Solution (in JAVA):

Solution:

/**
 *
 * @author meashish
 */
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStreamWriter;
import java.io.PrintStream;
import java.io.Serializable;
import java.math.BigInteger;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.HashSet;
import java.util.InputMismatchException;

public class Main {

    InputReader in;
    Printer out;

    long MOD = 1000000007;

    private void start() throws Exception {
        int n = in.nextInt();
        
        ArrayList<String> list = new ArrayList<>();
        while (n-- > 0) {
            list.add(in.next());
        }
        
        Collections.sort(list, (String s1, String s2) -> {
            String sb1 = s1 + s2;
            String sb2 = s2 + s1;
            
            return sb1.compareTo(sb2);
        });
        
        for (String s: list) {
            out.print(s);
        }
        out.println();
    }

    long power(long x, long n) {
        if (n <= 0) {
            return 1;
        }
        long y = power(x, n / 2);

        if ((n & 1) == 1) {
            return (((y * y) % MOD) * x) % MOD;
        }

        return (y * y) % MOD;
    }

    public int gcd(int a, int b) {
        a = Math.abs(a);
        b = Math.abs(b);
        return BigInteger.valueOf(a).gcd(BigInteger.valueOf(b)).intValue();
    }

    public int[] input(int n) {
        int a[] = new int[n];
        for (int i = 0; i < n; i++) {
            a[i] = in.nextInt();
        }

        return a;
    }

    public static void main(String[] args) throws Exception {
        InputReader in;
        PrintStream out;

        //in = new InputReader(new FileInputStream(new File("in.txt")));
        //out = new PrintStream("out.txt");
        in = new InputReader(System.in);
        out = System.out;

        Main main = new Main();

        main.in = in;
        main.out = new Printer(out);

        main.start();
        main.out.flush();
    }

    private static class InputReader {

        private InputStream stream;
        private byte[] buf = new byte[1024];
        private int curChar;
        private int numChars;
        private SpaceCharFilter filter;

        public InputReader(InputStream stream) {
            this.stream = stream;
        }

        public int read() {
            if (numChars == -1) {
                throw new InputMismatchException();
            }
            if (curChar >= numChars) {
                curChar = 0;
                try {
                    numChars = stream.read(buf);
                } catch (IOException e) {
                    throw new InputMismatchException();
                }
                if (numChars <= 0) {
                    return -1;
                }
            }
            return buf[curChar++];
        }

        public int nextInt() {
            int c = read();
            while (isSpaceChar(c)) {
                c = read();
            }
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            int res = 0;
            do {
                if (c < '0' || c > '9') {
                    throw new InputMismatchException();
                }
                res *= 10;
                res += c - '0';
                c = read();
            } while (!isSpaceChar(c));
            return res * sgn;
        }

        public String nextString() {
            int c = read();
            while (isSpaceChar(c)) {
                c = read();
            }
            StringBuilder res = new StringBuilder();
            do {
                res.appendCodePoint(c);
                c = read();
            } while (!isSpaceChar(c));
            return res.toString();
        }

        public double nextDouble() {
            int c = read();
            while (isSpaceChar(c)) {
                c = read();
            }
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            double res = 0;
            while (!isSpaceChar(c) && c != '.') {
                if (c == 'e' || c == 'E') {
                    return res * Math.pow(10, nextInt());
                }
                if (c < '0' || c > '9') {
                    throw new InputMismatchException();
                }
                res *= 10;
                res += c - '0';
                c = read();
            }
            if (c == '.') {
                c = read();
                double m = 1;
                while (!isSpaceChar(c)) {
                    if (c == 'e' || c == 'E') {
                        return res * Math.pow(10, nextInt());
                    }
                    if (c < '0' || c > '9') {
                        throw new InputMismatchException();
                    }
                    m /= 10;
                    res += (c - '0') * m;
                    c = read();
                }
            }
            return res * sgn;
        }

        public long nextLong() {
            int c = read();
            while (isSpaceChar(c)) {
                c = read();
            }
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            long res = 0;
            do {
                if (c < '0' || c > '9') {
                    throw new InputMismatchException();
                }
                res *= 10;
                res += c - '0';
                c = read();
            } while (!isSpaceChar(c));
            return res * sgn;
        }

        public boolean isSpaceChar(int c) {
            if (filter != null) {
                return filter.isSpaceChar(c);
            }
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

        public String next() {
            return nextString();
        }

        public interface SpaceCharFilter {

            public boolean isSpaceChar(int ch);
        }
    }

    private static class Printer {

        PrintStream out;
        StringBuilder buffer = new StringBuilder();
        boolean autoFlush;

        public Printer(PrintStream out) {
            this.out = out;
        }

        public Printer(PrintStream out, boolean autoFlush) {
            this.out = out;
            this.autoFlush = autoFlush;
        }

        public void println() {
            buffer.append("\n");

            if (autoFlush) {
                flush();
            }
        }

        public void println(int n) {
            println(Integer.toString(n));
        }

        public void println(long n) {
            println(Long.toString(n));
        }

        public void println(double n) {
            println(Double.toString(n));
        }

        public void println(float n) {
            println(Float.toString(n));
        }

        public void println(boolean n) {
            println(Boolean.toString(n));
        }

        public void println(char n) {
            println(Character.toString(n));
        }

        public void println(byte n) {
            println(Byte.toString(n));
        }

        public void println(short n) {
            println(Short.toString(n));
        }

        public void println(Object o) {
            println(o.toString());
        }

        public void println(Object[] o) {
            println(Arrays.deepToString(o));
        }

        public void println(String s) {
            buffer.append(s).append("\n");

            if (autoFlush) {
                flush();
            }
        }

        public void print(char s) {
            buffer.append(s);

            if (autoFlush) {
                flush();
            }
        }

        public void print(String s) {
            buffer.append(s);

            if (autoFlush) {
                flush();
            }
        }

        public void flush() {
            try {
                BufferedWriter log = new BufferedWriter(new OutputStreamWriter(out));
                log.write(buffer.toString());

                log.flush();
                buffer = new StringBuilder();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

    private class Pair<T, U> implements Serializable {

        int x;
        int index;
        int ans = 0;
        private T key;

        public T getKey() {
            return key;
        }

        private U value;

        public U getValue() {
            return value;
        }

        public Pair(T key, U value) {
            this.key = key;
            this.value = value;
        }

        @Override
        public String toString() {
            return key + "=" + value;
        }

        @Override
        public boolean equals(Object obj) {
            if (obj == null) {
                return false;
            }
            if (getClass() != obj.getClass()) {
                return false;
            }

            final Pair other = (Pair) obj;
            if (!this.key.equals(other.key)) {
                return false;
            }

            return this.value.equals(other.value);
        }

        @Override
        public int hashCode() {
            return key.hashCode() + 13 * value.hashCode();
        }
    }

    private class PairSet<T, S> {

        HashMap<T, HashSet<S>> map = new HashMap<>();

        public void add(T a, S b) {
            if (map.containsKey(a)) {
                map.get(a).add(b);
            }

            HashSet<S> set = new HashSet<>();
            set.add(b);
            map.put(a, set);
        }

        public boolean contains(T a, S b) {
            if (map.containsKey(a)) {
                return map.get(a).contains(b);
            }

            return false;
        }
    }

    private class Bit {

        int N;
        long ft1[], ft2[];

        Bit(int n) {
            N = n;
            ft1 = new long[N + 1];
            ft2 = new long[N + 1];
        }

        void update(long ft[], int p, long v) {
            for (; p <= N; p += p & (-p)) {
                ft[p] += v;
//                ft[p] %= MOD;
            }
        }

        void update(int a, int b, long v) {
            update(ft1, a, v);
            update(ft1, b + 1, -v);
            update(ft2, a, v * (a - 1));
            update(ft2, b + 1, -v * b);
        }

        long query(long ft[], int b) {
            long sum = 0;
            for (; b > 0; b -= b & (-b)) {
                sum += ft[b];
//                sum %= MOD;
            }

            return sum;
        }

        long query(int b) {
            return query(ft1, b) * b - query(ft2, b);
        }

        long query(int a, int b) {
            return query(b) - query(a - 1);
        }
    }
}