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.*;
import java.math.BigInteger;

public class Tests{
	static Scanner in = new Scanner (System.in);
	//static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

	//static long MOD = 1000000007;

	static PrintWriter out = new PrintWriter (System.out);
	static ArrayList <String> list = new ArrayList <String>();


	public static void main (String []args){
		
		int n = in.nextInt();
		
		for(int i = 0 ; i<n ; i++){
			String s = in.next();
			
			list.add(s);
		}
		
		Collections.sort(list,new sort ());
		
		//out.println(list);
		
		for(String s : list){
			out.print(s);
		}
	

		
	
	
		
	   out.flush();
		out.close();
				
	}
	final static class sort implements Comparator <String> {

		@Override
		public int compare(String s1, String s2) {
			int com = (s1+s2).compareTo(s2+s1) ;
			if(com > 0) return 1 ;
			
			else if (com < 0 ) return -1 ;
			
			else return 0;
		}
		
	}
	
	
	
}