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.*;

public class CF632C {
	static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

	public static void main(String[] args) throws IOException {
		int n = Integer.parseInt(br.readLine());
		String[] arr = new String[n];

		int maxLength = 0;

		for(int i = 0; i < n; i++) {
			arr[i] = br.readLine();
		}

		Arrays.sort(arr, new Comparator<String>() {
			public int compare(String o1, String o2) {
		        return (o1 + o2).compareTo(o2 + o1);
		    }
		});

		System.out.println(String.join("", arr));

		// int maxLength = 0;

		// for(int i = 0; i < n; i++) {
		// 	arr[i] = br.readLine();
		// 	maxLength = Math.max(maxLength, arr[i].length());
		// }

		// Entry[] map = padStrings(arr, maxLength);
		// Arrays.sort(map);
		// StringBuilder ans = new StringBuilder();

		// for(Entry e : map) {
		// 	System.out.println(e.string);
		// 	ans.append(arr[e.index]);
		// }

		// System.out.println(ans);
	}

	// public static Entry[] padStrings(String[] arr, int maxLength) {
	// 	Entry[] map = new Entry[arr.length];

	// 	for(int i = 0; i < arr.length; i++) {
	// 		StringBuilder str = new StringBuilder(arr[i]);
	// 		for(int j = arr[i].length(); j < maxLength; j++) {
	// 			str.append("z");
	// 		}

	// 		map[i] = new Entry(str.toString(), i);
	// 	}

	// 	return map;
	// }

	// // public static TreeMap<String, Integer> padStrings(String[] arr, int maxLength) {
	// // 	TreeMap<String, Integer> map = new TreeMap<String, Integer>();

	// // 	for(int i = 0; i < arr.length; i++) {
	// // 		StringBuilder str = new StringBuilder(arr[i]);
	// // 		for(int j = arr[i].length(); j < maxLength; j++) {
	// // 			str.append("z");
	// // 		}

	// // 		map.put(str.toString(), i);
	// // 	}

	// // 	return map;
	// // }

	// static class Entry implements Comparable<Entry> {
	// 	public String string;
	// 	public int index;

	// 	public Entry(String s, int i) {
	// 		string = s;
	// 		index = i;
	// 	}

	// 	public int compareTo(Entry a) {
	// 		return this.string.compareTo(a.string);
	// 	}
	// }

}