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:
import java.io.*;
import java.util.*;

import static java.lang.Math.*;


public class Main {
    FastScanner in;
    PrintWriter out;

    static final String FILE = "";

    public void solve() {
        ArrayList<String> list = new ArrayList<>();
        int n = in.nextInt();
        for (int i = 0; i < n; i++)
            list.add(in.next());
        list.sort((a, b) -> {
            String c = a + b;
            String d = b + a;
            for (int i = 0; i < c.length(); i++) {
                if (c.charAt(i) > d.charAt(i)) {
                    return 1;
                } else if (c.charAt(i) < d.charAt(i)) {
                    return -1;
                }
            }
            return 0;
        });
        for (String s : list)
            out.print(s);
    }

    public void run() {
        if (FILE.equals("")) {
            in = new FastScanner(System.in);
            out = new PrintWriter(System.out);
        } else {
            try {
                in = new FastScanner(new FileInputStream(FILE +
                        ".in"));
                out = new PrintWriter(new FileOutputStream(FILE +
                        ".out"));
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            }
        }
        solve();
        out.close();
    }

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

    class FastScanner {
        BufferedReader br;
        StringTokenizer st;

        public FastScanner(InputStream is) {
            br = new BufferedReader(new InputStreamReader(is));
        }

        public String next() {
            while (st == null || !st.hasMoreTokens()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        public String nextLine() {
            st = null;
            try {
                return br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
                return "";
            }
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

        public long nextLong() {
            return Long.parseLong(next());
        }

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

        public float nextFloat() {
            return Float.parseFloat(next());
        }
    }

    class Pair<A extends Comparable<A>, B extends Comparable<B>>
            implements Comparable<Pair<A, B>> {
        public A a;
        public B b;

        public Pair(A a, B b) {
            this.a = a;
            this.b = b;
        }

        @Override
        public int compareTo(Pair<A, B> o) {
            if (o == null || o.getClass() != getClass())
                return 1;
            int cmp = a.compareTo(o.a);
            if (cmp == 0)
                return b.compareTo(o.b);
            return cmp;
        }

        @Override
        public boolean equals(Object o) {
            if (this == o) return true;
            if (o == null || getClass() != o.getClass()) return false;

            Pair<?, ?> pair = (Pair<?, ?>) o;

            if (a != null ? !a.equals(pair.a) : pair.a != null) return
                    false;
            return !(b != null ? !b.equals(pair.b) : pair.b != null);
        }
    }

    class PairInt extends Pair<Integer, Integer> {
        public PairInt(Integer u, Integer v) {
            super(u, v);
        }
    }

    class PairLong extends Pair<Long, Long> {
        public PairLong(Long u, Long v) {
            super(u, v);
        }
    }

}