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

/**
 * @author ramilagger
 *
 */
public class Main {

    final boolean ONLINE_JUDGE = System.getProperty("ONLINE_JUDGE") != null;
    final BufferedReader br;
    final PrintWriter pw;
    StringTokenizer st;

    public void solve() throws Exception {
        int n = nextInt();
        String[] a = new String[n];
        for (int i = 0; i < n; i++) {
            a[i] = next();
        }
        Arrays.sort(a , (o1, o2) -> (o1 + o2).compareTo(o2 + o1));
        for (String s : a) {
            pw.print(s);
        }
        pw.println();
    }


    public void run() throws Exception{
        long start = System.currentTimeMillis();
        solve();
        if(!ONLINE_JUDGE){
            long end = System.currentTimeMillis();
            System.err.println(end - start + " ms");
        }
        pw.close();
    }

    public Main() throws Exception {

        br = (ONLINE_JUDGE) ? new BufferedReader(new InputStreamReader(System.in))
                : new BufferedReader(new FileReader("in.txt"));

        pw = (ONLINE_JUDGE) ?
                new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.out)))
                : new PrintWriter(new BufferedWriter(new FileWriter("out.txt")));

    }

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

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

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

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

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

    public BigInteger nextBigInteger () throws IOException {
        return new BigInteger(next());
    }

    public String nextLine() throws IOException {
        while (st == null || !st.hasMoreTokens()) {
            return br.readLine();
        }
        StringBuilder s = new StringBuilder(st.nextToken());
        while (st.hasMoreTokens()){
            s.append(" " + st.nextToken());
        }
        return s.toString();
    }

}