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.*;
import java.util.concurrent.CompletableFuture;
import java.util.function.BiConsumer;
import java.util.function.BiFunction;
import java.util.function.Consumer;
import java.util.function.Function;
import java.util.stream.Collectors;
import java.util.stream.IntStream;
import java.util.stream.Stream;
import java.util.Map.Entry;

public class Main implements Runnable {
    static final int MOD = (int) 1e9 + 7;
    static final int MI = (int) 1e9;
    static final long ML = (long) 1e18;
    static final Reader in = new Reader();
    static final PrintWriter out = new PrintWriter(System.out);
    StringBuilder answer = new StringBuilder();
    Random random = new Random(751454315315L + System.currentTimeMillis());

    public static void main(String[] args) {
        new Thread(null, new Main(), "persefone", 1 << 28).start();
    }

    @Override
    public void run() {
        solve();
        printf();
        flush();
    }

    void solve() {
        int n = in.nextInt();
        String[] s = new String[n];
        for (int i = 0; i < n; i++) {
            s[i] = in.next();
        }
        if (n == 1) {
            printf(s[0]);
        } else {
            Arrays.sort(s, (s1, s2) -> s1.concat(s2).compareTo(s2.concat(s1)));
            for (int i = 0; i < n; i++) {
                add(s[i]);
            }
        }

    }

    static class SegTreeMin {
        private int n;
        private int[] min;

        public SegTreeMin(int n) {
            this.n = n;
            this.min = new int[4 * n + 4];
            Arrays.fill(min, MI);
        }

        private int calc(int x, int y) {
            return Math.min(x, y);
        }

        private void update(int currentVertex, int currentLeft, int currentRight, int pos, int value) {
            if (currentLeft == currentRight) min[currentVertex] = value;
            else {
                int mid = currentLeft + currentRight >> 1, doubleVex = currentVertex << 1;
                if (pos <= mid)
                    update(doubleVex, currentLeft, mid, pos, value);
                else
                    update(doubleVex + 1, mid + 1, currentRight, pos, value);
                min[currentVertex] = calc(min[doubleVex], min[doubleVex + 1]);
            }
        }

        public void update(int pos, int value) {
            update(1, 0, n - 1, pos, value);
        }

        private int get(int currentVertex, int currentLeft, int currentRight, int left, int right) {
            if (left > currentRight || right < currentLeft) return MI;
            if (currentLeft >= left && currentRight <= right) return min[currentVertex];
            int mid = currentLeft + currentRight >> 1, doubleVex = currentVertex << 1;
            return calc(get(doubleVex, currentLeft, mid, left, right), get(doubleVex + 1, mid + 1, currentRight, left, right));
        }

        public int get(int left, int right) {
            return get(1, 0, n - 1, left, right);
        }
    }

    void printf() {
        out.print(answer);
    }

    void close() {
        out.close();
    }

    void flush() {
        out.flush();
    }

    void printf(Stream<?> str) {
        str.forEach(o -> add(o, " "));
        add("\n");
    }


    void printf(Object... obj) {
        printf(false, obj);
    }

    void printfWithDescription(Object... obj) {
        printf(true, obj);
    }


    private void printf(boolean b, Object... obj) {

        if (obj.length > 1) {
            for (int i = 0; i < obj.length; i++) {
                if (b) add(obj[i].getClass().getSimpleName(), " - ");
                if (obj[i] instanceof Collection<?>) {
                    printf((Collection<?>) obj[i]);
                } else if (obj[i] instanceof int[][]) {
                    printf((int[][]) obj[i]);
                } else if (obj[i] instanceof long[][]) {
                    printf((long[][]) obj[i]);
                } else if (obj[i] instanceof double[][]) {
                    printf((double[][]) obj[i]);
                } else printf(obj[i]);
            }
            return;
        }

        if (b) add(obj[0].getClass().getSimpleName(), " - ");
        printf(obj[0]);
    }

    void printf(Object o) {
        if (o instanceof int[])
            printf(Arrays.stream((int[]) o).boxed());
        else if (o instanceof char[])
            printf(new String((char[]) o));
        else if (o instanceof long[])
            printf(Arrays.stream((long[]) o).boxed());
        else if (o instanceof double[])
            printf(Arrays.stream((double[]) o).boxed());
        else if (o instanceof boolean[]) {
            for (boolean b : (boolean[]) o) add(b, " ");
            add("\n");
        } else
            add(o, "\n");
    }

    void printf(int[]... obj) {
        for (int i = 0; i < obj.length; i++) printf(obj[i]);
    }

    void printf(long[]... obj) {
        for (int i = 0; i < obj.length; i++) printf(obj[i]);
    }

    void printf(double[]... obj) {
        for (int i = 0; i < obj.length; i++) printf(obj[i]);
    }

    void printf(boolean[]... obj) {
        for (int i = 0; i < obj.length; i++) printf(obj[i]);
    }

    void printf(Collection<?> col) {
        printf(col.stream());
    }

    <T, K> void add(T t, K k) {
        if (t instanceof Collection<?>) {
            ((Collection<?>) t).forEach(i -> add(i, " "));
        } else if (t instanceof Object[]) {
            Arrays.stream((Object[]) t).forEach(i -> add(i, " "));
        } else
            add(t);
        add(k);
    }


    <T> void add(T t) {
        answer.append(t);
    }

    static class Reader {
        private BufferedReader br;
        private StringTokenizer st;

        Reader() {
            br = new BufferedReader(new InputStreamReader(System.in));
        }

        Reader(String fileName) throws FileNotFoundException {
            br = new BufferedReader(new FileReader(fileName));
        }

        boolean isReady() throws IOException {
            return br.ready();
        }

        String next() {
            try {
                while (st == null || !st.hasMoreTokens()) {
                    st = new StringTokenizer(br.readLine());
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
            return st.nextToken();
        }

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

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

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

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

        String nextLine() {
            String s = "";
            try {
                s = br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return s;
        }
    }
}