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.awt.Point;
import java.io.*;
import java.util.*;
import java.math.*;
import static java.lang.Math.*;
import static java.lang.Integer.parseInt;
import static java.lang.Long.parseLong;
import static java.lang.Double.parseDouble;
import static java.lang.String.*;

public class Main {

    static StringBuilder a = new StringBuilder();

    public static void main(String[] args) throws IOException {
        //BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
//(new FileReader("input.in"));
        StringBuilder out = new StringBuilder();
//        StringTokenizer tk;
//        tk = new StringTokenizer(in.readLine());
        //Scanner Reader = new Scanner(System.in);
        Reader.init(System.in);
        int n=Reader.nextInt();
          str [] a = new str[n];
          for (int i = 0; i < n; i++) {
              String c=Reader.next();
              a[i]=new str(c, c);
        }
       
          Arrays.sort(a,new str());
          for (int i = 0; i < n; i++) {
              out.append(a[i].y);
        }
          System.out.println(out);
         
    }
    static String ss (String x){
    char[]a=x.toCharArray();
    Arrays.sort(a);
    return new String(a);
    
    }
}
class str implements Comparator<str>{
String x,y;
public str(){}
public str(String a,String b){
x=a;
y=b;
}

    @Override
    public int compare(str a, str b) {
     return (a.x+b.x).compareTo(b.x+a.x);
    }

}

class Reader {

    static StringTokenizer tokenizer;
    static BufferedReader reader;

    public static void init(InputStream input) throws UnsupportedEncodingException {
        reader = new BufferedReader(new InputStreamReader(input, "UTF-8"));
        tokenizer = new StringTokenizer("");
    }

    public static String next() throws IOException {
        while (!tokenizer.hasMoreTokens()) {
            tokenizer = new StringTokenizer(reader.readLine());
        }
        return tokenizer.nextToken();
    }

    public static String nextLine() throws IOException {
        return reader.readLine();
    }

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

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

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