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.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.*;

public class Main {
    public static void main(String[] args) {
//     Test.testing();
        ConsoleIO io = new ConsoleIO();
        new Main(io).solve();
        io.flush();
    }
    ConsoleIO io;
    Main(ConsoleIO io) {
        this.io = io;
    }

    ArrayList<ArrayList<Integer>> gr1;
    boolean[] visit;
    //

    class Pair{
        public Pair(int a, int b){
            this.a = a;
            this.b = b;
        }
        public int a;
        public int b;
    }

    class Edge {
        public Edge(int c, int u,int v) {
            this.u = u;
            this.v = v;
            this.c = c;
        }
        public int u;
        public int v;
        public int c;
    }

    class Two{
        public Two(String a, String b){
            this.a = a;
            this.b = b;
        }
        public String a;
        public String b;
    }

    long MOD = 1_000_000_007;
    int n,m,k,fn;
    int[][] map;
    public void solve() {
        n = io.readInt();
        Two[] all = new Two[n];

        for(int i = 0;i<n;i++) {
            String s = io.readLine().trim();
            StringBuilder sb = new StringBuilder(s);

            for (int j = 0; sb.length() < 150; j++) {
                sb.append(sb.charAt(j));
            }

            all[i] = new Two(s, sb.toString());
        }

        Arrays.sort(all, (Two t1, Two t2)-> t1.b.compareTo(t2.b));
        StringBuilder res = new StringBuilder();
        for(int i = 0;i<n;i++)
            res.append(all[i].a);

        io.writeLine(res.toString());
    }


    long gcd(long a, long b) {
        if (a < b) return gcd(b, a);
        if (b == 0) return a;
        return gcd(b, a % b);
    }
}

class ConsoleIO {
    BufferedReader br;
    PrintWriter out;
    public ConsoleIO(){br = new BufferedReader(new InputStreamReader(System.in));out = new PrintWriter(System.out);}
    public void flush(){this.out.close();}
    public void writeLine(String s) {this.out.println(s);}
    public void writeInt(int a) {this.out.print(a);this.out.print(' ');}
    public void writeWord(String s){
        this.out.print(s);
    }
    public String readLine() {try {return br.readLine();}catch (Exception ex){ return "";}}
    public long readLong() {
        return Long.parseLong(this.readLine());
    }
    public int readInt() {
        return Integer.parseInt(this.readLine().trim());
    }
    public long[] readLongArray() {
        String[]n=this.readLine().trim().split("\\s+");long[]r=new long[n.length];
        for(int i=0;i<n.length;i++)r[i]=Long.parseLong(n[i]);
        return r;
    }
    public int[] readIntArray() {
        String[]n=this.readLine().trim().split("\\s+");int[]r=new int[n.length];
        for(int i=0;i<n.length;i++)r[i]=Integer.parseInt(n[i]);
        return r;
    }
    public void writeIntArray(int[] a) {
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < a.length; i++) {if (i > 0) sb.append(' ');sb.append(a[i]);}
        this.writeLine(sb.toString());
    }
}