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.io.*;
import java.util.*;


public class Main {
    public static void main(String[] args) throws IOException {
        InputStream inputStream = System.in;
//        InputStream inputStream = new FileInputStream("sum.in");
        OutputStream outputStream = System.out;
//        OutputStream outputStream = new FileOutputStream("sum.out");


//        Path path = Paths.get(URI.create("file:///foo/bar/Main.java"));
//        System.out.print(path.getName(200));

//        Path p = Paths.get("/foo/bar/Main.java");
//        for (Path e : p) {
//            System.out.println(e);
//        }

        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        Answer solver = new Answer();
        solver.solve(in, out);
        out.close();
    }
}

class Answer {
    private final int INF = (int) (1e9 + 7);
    private final int MOD = (int) (1e9 + 7);
    private final int MOD1 = (int) (1e6 + 3);
    private final long INF_LONG = (long) (1e18 + 1);
    private final double EPS = 1e-9;

    private long gcd(long a, long b) {
        return (b == 0) ? a : gcd(b, a % b);
    }

    public void solve(InputReader in, PrintWriter out) throws IOException {
        int n = in.nextInt();

        List<String> list = new ArrayList<>();
        for (int i = 0; i < n; i++) {
            String s = in.next();
            list.add(s);
        }

        Collections.sort(list, new Comparator<String>() {
            @Override
            public int compare(String o1, String o2) {
                String s1 = o1 + o2;
                String s2 = o2 + o1;
                return s1.compareTo(s2);
            }
        });

        for (String value : list) {
            out.print(value);
        }

    }
}

class InputReader {
    private BufferedReader reader;
    private StringTokenizer tokenizer;

    InputReader(InputStream stream) {
        reader = new BufferedReader(new InputStreamReader(stream), 32768);
        tokenizer = null;
    }

    public String next() {
        while (tokenizer == null || !tokenizer.hasMoreTokens()) {
            try {
                tokenizer = new StringTokenizer(reader.readLine());
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }
        return tokenizer.nextToken();
    }

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

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

    public int[] nextArrayInt(int count) {
        int[] a = new int[count];
        for (int i = 0; i < count; i++) {
            a[i] = nextInt();
        }
        return a;
    }

    public long[] nextArrayLong(int count) {
        long[] a = new long[count];
        for (int i = 0; i < count; i++) {
            a[i] = nextLong();
        }
        return a;
    }
}