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

public class Main {

    static class FastReader {
        BufferedReader br;
        StringTokenizer st;

        FastReader() {
            br = new BufferedReader(new InputStreamReader(System.in));
        }

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

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

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

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

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


    public static void main(String[] args) throws IOException {
        FastReader ip = new FastReader();
        OutputStream output = System.out;
        PrintWriter out = new PrintWriter(output);
        int n=ip.nextInt();
        String arr[]=new String[n];
        for(int  i=0;i<n;i++){
            arr[i]=ip.nextLine();
        }
        Arrays.sort(arr, new Comparator<String>() {
            @Override
            public int compare(String o1, String o2) {
                if((o1+o2).compareTo(o2+o1)>0){
                    return 1;
                }else if((o1+o2).compareTo(o2+o1)<0){
                  return -1;
                }else{
                    return 0;
                }

            }
        });
        StringBuilder str=new StringBuilder("");
        for(int i=0;i<arr.length;i++){
            str.append(arr[i]);
        }
        out.println(str);
        out.close();
    }
}