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

public class ForProblems {

    Random rnd = new Random();

    public class OtherString implements Comparable<OtherString> {

        public String str;

        OtherString(String str) {
            this.str = str;
        }

        @Override
        public int compareTo(OtherString str) {

            if ((str.str + this.str).compareTo(this.str + str.str) > 0) {
                return 1;
            }
            if ((str.str + this.str).compareTo(this.str + str.str) < 0) {
                return -1;
            }
            return 0;
        }
    }

    void solve() throws IOException {

        int n = readInt();
        ArrayList<OtherString> a = new ArrayList<OtherString>();
        for (int i = 0; i < n; ++i) {
            OtherString tmp = new OtherString(readString());
            a.add(tmp);
        }

        Collections.sort(a);

        for (int i = n - 1; i >= 0; --i)
            out.print(a.get(i).str);
    }


    BufferedReader in;
    PrintWriter out;
    StringTokenizer tok = new StringTokenizer("");

    final boolean ONLINE_JUDGE = System.getProperty("ONLINE_JUDGE") != null;

    public static void main(String[] args){

        new ForProblems().run();
    }

    public void run() {

        try {
            long timeBegin = System.currentTimeMillis();
            Locale.setDefault(Locale.US);

            init();
            solve();

            out.close();

            long timeEnd = System.currentTimeMillis();
            System.err.println("Time = " + (timeEnd - timeBegin));
        } catch (Exception e) {
            e.printStackTrace(System.err);
            System.exit(-1);
        }
    }

    void init() throws FileNotFoundException {

        Locale.setDefault(Locale.US);

        if (ONLINE_JUDGE) {
            in = new BufferedReader(new InputStreamReader(System.in));
            out = new PrintWriter(System.out);
        } else {
            in = new BufferedReader(new FileReader("input.txt"));
            out = new PrintWriter("output.txt");
        }
    }

    String readString() throws IOException {
        while(!tok.hasMoreTokens()){
            try{
                tok = new StringTokenizer(in.readLine());
            } catch (Exception e) {
                return null;
            }
        }
        return tok.nextToken();
    }

    int readInt() throws IOException {
        return Integer.parseInt(readString());
    }

    long readLong() throws IOException {
        return Long.parseLong(readString());
    }

}