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
/*      MOHD SADIQ        */


import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.math.BigInteger;
import java.util.*;
import java.util.ArrayList;

public class Main {

    private static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

    private  long longVal() throws IOException{
        return Long.parseLong(br.readLine().trim());
    }
    private  int intVal() throws IOException{
        return Integer.parseInt(br.readLine().trim());
    }
    private  double doubleVal() throws IOException{
        return Double.parseDouble(br.readLine().trim());
    }
    private  int[] intArr() throws IOException{
        String[] s = br.readLine().trim().split(" ");
        int n = s.length;
        int[] a = new int[n];
        for (int i = 0; i < n; i++) {
            a[i] = Integer.parseInt(s[i]);
        }
        return a;
    }
    private  long[] longArr() throws IOException {
        String[] s = br.readLine().trim().split(" ");
        int n = s.length;
        long[] a = new long[n];
        for (int i = 0; i < n; i++) {
            a[i] = Long.parseLong(s[i]);
        }
        return a;
    }
    private  double[] doubleArr() throws IOException {
        String[] s = br.readLine().trim().split(" ");
        int n = s.length;
        double[] a = new double[n];
        for (int i = 0; i < n; i++) {
            a[i] = Double.parseDouble(s[i]);
        }
        return a;
    }
    private String[] stringArr() throws IOException{
        String[] s = br.readLine().trim().split(" ");
        return s;
    }
    private  char[] charArr() throws IOException{
        return br.readLine().trim().toCharArray();
    }

    private static boolean check(String s){
        for(int i=0;i<s.length()-1;i++){
            if(s.charAt(i)<s.charAt(i+1)){
                return true;
            }
        }
        return false;
    }

    private static String solve() throws IOException {

        Main obj = new Main();
        int n = obj.intVal();
        String[] arr =new String[n];
        ArrayList<String> al[] = new ArrayList[26];
        for(int i=0;i<26;i++)
            al[i] = new ArrayList<>();
        for(int i=0;i<n;i++){
            arr[i] = br.readLine().trim();
            al[arr[i].charAt(0)-'a'].add(arr[i]);
        }

        StringBuffer ans = new StringBuffer();

        Arrays.sort(arr, new Comparator<String>() {
            @Override
            public int compare(String o1, String o2) {
//                int i = 0;
//                int min = Math.min(o1.length(),o2.length());
//                if(o1.substring(0,min).compareTo(o2.substring(0,min))==0){
//
//                }
                return (o1+o2).compareTo(o2+o1);
            }
        });
        for(String i:arr){
            ans.append(i);
        }
        return ans+"";
    }


    public static void main(String[] args) throws IOException {
        Main ob = new Main();
//        int total_test_case = ob.intVal();
        int total_test_case = 1;
        StringBuffer ans = new StringBuffer();
        String k ;
        for(int test_case =0;test_case<total_test_case;test_case++){
            k = Main.solve();
//            System.out.println(k);
            ans.append(k+"");
        }
        System.out.print(ans);
    }
}