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
/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */

/**
 *
 * @author sarthak
 */
import java.util.*;
import java.math.*;
import java.io.*;

public class eduRnd9_C {

    static class FastScanner {

        BufferedReader br;
        StringTokenizer st;

        public FastScanner(InputStream is) {
            br = new BufferedReader(new InputStreamReader(is));
        }

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

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

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

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

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

    static class P implements Comparable {

        private int x, y;

        public P(int x, int y) {
            this.x = x;
            this.y = y;
        }

        public int hashCode() {
            return (x * 31) ^ y;
        }

        public boolean equals(Object o) {
            if (o instanceof P) {
                P other = (P) o;
                return (x == other.x && y == other.y);
            }
            return false;
        }

        public int compareTo(Object obj) {
            P l = (P) obj;
            if (this.x == l.x) {
                if (this.y == l.y) {
                    return 0;
                }
                return (this.y < l.y) ? -1 : 1;
            }
            return (this.x < l.x) ? -1 : 1;
        }
    }

   
    public static void main(String[] args) {

        FastScanner s = new FastScanner(System.in);
        StringBuilder op = new StringBuilder();

        int n = s.nextInt();
        String[] a = new String[n];
        for (int i = 0; i < n; i++) {
            a[i] = s.next();
        }
        Arrays.sort(a, new Comp());
        for(String st:a)
            op.append(st);
        System.out.println(op);

    }

}

 class Comp implements Comparator<String>
{
	
	public int compare(String his,String that)
	{
	return (his+that).compareTo(that+his);	
	}

}
