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
import java.io.*;
import java.util.*;
import java.text.DecimalFormat;
import java.util.concurrent.ConcurrentMap;

public class SSC {
    static long mod=(long)1e9+7;
    static long mod1=998244353;
    static InputStream inputStream = System.in;
    static OutputStream outputStream = System.out;
    static InputReader in = new InputReader(inputStream);
    static PrintWriter out = new PrintWriter(outputStream);

    public static void main(String[] args) throws IOException {

        int n = in.nextInt();
        ArrayList<String> arr =new ArrayList<>();
        for(int i = 0;i<n;i++) arr.add(in.next());

        arr.sort(new sortLex());
        for(String s:arr)
            out.print(s);

        out.println();
        out.close();
    }

    static class sortLex implements Comparator<String>{
        public int compare(String a, String b){
           return (a+b).compareTo(b+a);
        }
    }


    static final Random random=new Random();

    static void ruffleSort(int[] a) {
        int n=a.length;//shuffle, then sort
        for (int i=0; i<n; i++) {
            int oi=random.nextInt(n), temp=a[oi];
            a[oi]=a[i]; a[i]=temp;
        }
        Arrays.sort(a);
    }
    static long gcd(long x, long y){
        if(x==0)
            return y;
        if(y==0)
            return x;
        long r=0, a, b;
        a = Math.max(x, y);
        b = Math.min(x, y);
        r = b;
        while(a % b != 0){
            r = a % b;
            a = b;
            b = r;
        }
        return r;
    }
    static long modulo(long a,long b,long c){
        long x=1,y=a%c;
        while(b > 0){
            if(b%2 == 1)
                x=(x*y)%c;
            y = (y*y)%c;
            b = b>>1;
        }
        return  x%c;
    }
    public static void debug(Object... o){
        System.err.println(Arrays.deepToString(o));
    }

    static int upper_bound(int[] arr,int n,int x){
        int mid;
        int low=0;
        int high=n;
        while(low<high){
            mid=low+(high-low)/2;
            if(x>=arr[mid])
                low=mid+1;
            else
                high=mid;
        }
        return low;
    }

    static int lower_bound(int[] arr,int n,int x){
        int mid;
        int low=0;
        int high=n;
        while(low<high){
            mid=low+(high-low)/2;
            if(x<=arr[mid])
                high=mid;
            else
                low=mid+1;
        }
        return low;
    }
    static String printPrecision(double d){
        DecimalFormat ft = new DecimalFormat("0.00000000000");
        return String.valueOf(ft.format(d));
    }
    static int countBit(long mask){
        int ans=0;
        while(mask!=0){
            mask&=(mask-1);
            ans++;
        }
        return ans;
    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

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

        public int[] readArray(int n) {
            int[] arr = new int[n];
            for (int i = 0; i < n; i++) arr[i] = nextInt();
            return arr;
        }
    }
}