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:
//package edu_9;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.StringTokenizer;


public class C {

    static StringTokenizer st;
    static BufferedReader br;
    static PrintWriter pw;
    public static void main(String[] args) throws IOException {
        br = new BufferedReader(new InputStreamReader(System.in));
        pw = new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.out)));
        int n = nextInt();
        string []s = new string[n+1];
        for (int i = 1; i <= n; i++) {
			s[i] = new string(next());
		}
        Arrays.sort(s,1,n+1);
        for (int i = 1; i <= n; i++) {
			pw.print(s[i].s);
		}
        pw.close();
    }

    private static int nextInt() throws IOException {
        return Integer.parseInt(next());
    }
//    private static long nextLong() throws IOException {
//        return Long.parseLong(next());
//    }
//    private static double nextDouble() throws IOException {
//        return Double.parseDouble(next());
//    }
    private static String next() throws IOException {
        while (st==null || !st.hasMoreTokens())
            st = new StringTokenizer(br.readLine());
        return st.nextToken();
    }
}
class string implements Comparable<string>{
	String s;
	string(String s2){
		this.s=s2;
	}	
	public int compareTo(string o) {
//		if(this.s.length()==o.s.length())
			return (this.s.concat(o.s)).compareTo(o.s.concat(this.s));
//		return -this.s.length()+o.s.length();
	}
}