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.Scanner;
import java.util.Arrays;

public class Edu9C {

    public static void main(String [] args) {
        Scanner in = new Scanner(System.in);
        TaskC task = new TaskC();
        task.solve(in);
    }
}

class Word implements Comparable<Word> {

    private String word;

    public Word(String word) {
        this.word = word;
    }

    public String getWord() { return this.word; }
    public int compareTo(Word other) {
        return this.word.concat(other.getWord()).compareTo(other.getWord().concat(this.word));
    }
    public String toString() { return this.word; }
}

class TaskC {

    public void solve(Scanner in) {
        int N = in.nextInt();
        in.nextLine();

        Word [] dict = new Word[N];
        for (int i = 0; i < N; i++) {
            dict[i] = new Word(in.nextLine());
        }

        Arrays.sort(dict);

        for (Word w : dict) {
            System.out.printf("%s", w);
        }
        System.out.printf("\n");
    }
}