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 com.sun.org.apache.xml.internal.utils.StringComparable;

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

public final class Contest{
    BufferedReader br;
    PrintWriter out;
    StringTokenizer st;
    boolean eof;


    void solve() throws IOException {
        int n = nextInt();
        String[] strings = new String[n];
        for(int i = 0 ; i < n ; i++) {
            strings[i] = nextString();
        }
        Arrays.sort(strings, new StrComp());
        StringBuilder builder = new StringBuilder();
        for(String s : strings) {
            builder.append(s);
        }
        out.print(builder);
    }

    Contest() throws IOException {
        br = new BufferedReader(new InputStreamReader(System.in));
        out = new PrintWriter(System.out);
        solve();
        out.close();
    }

    public class StrComp implements Comparator<String>{
        @Override
        public int compare(String o1, String o2) {
            String conc1 = o1.concat(o2);
            String conc2 = o2.concat(o1);
            return conc1.compareTo(conc2);
        }
    }
    public static void main(String[] args) throws IOException {
        new Contest();
    }

     String nextToken() {
        while (st == null || !st.hasMoreTokens()) {
            try {
                st = new StringTokenizer(br.readLine());
            } catch (Exception e) {
                eof = true;
                return null;
            }
        }
        return st.nextToken();
    }

    String nextString() {
        try {
            return br.readLine();
        } catch (IOException e) {
            eof = true;
            return null;
        }
    }

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

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

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