Problem: There are n distinct points on a coordinate line, the coordinate of i-th point equals to x_i. Choose a subset of the given set of points such that the distance between each pair of points in a subset is an integral power of two. It is necessary to consider each pair of points, not only adjacent. Note that any subset containing one element satisfies the condition above. Among all these subsets, choose a subset with maximum possible size.

In other words, you have to choose the maximum possible number of points x_{i_1}, x_{i_2}, ..., x_{i_m} such that for each pair x_{i_j}, x_{i_k} it is true that |x_{i_j} - x_{i_k}| = 2^d where d is some non-negative integer number (not necessarily the same for each pair of points).

Input

The first line contains one integer n (1 ≤ n ≤ 2 ⋅ 10^5) — the number of points.

The second line contains n pairwise distinct integers x_1, x_2, ..., x_n (-10^9 ≤ x_i ≤ 10^9) — the coordinates of points.

Output

In the first line print m — the maximum possible number of points in a subset that satisfies the conditions described above.

In the second line print m integers — the coordinates of points in the subset you have chosen.

If there are multiple answers, print any of them.

Examples

Input

6
3 5 4 7 10 12


Output

3
7 3 5

Input

5
-1 2 5 8 11


Output

1
8

Note

In the first example the answer is [7, 3, 5]. Note, that |7-3|=4=2^2, |7-5|=2=2^1 and |3-5|=2=2^1. You can't find a subset having more points satisfying the required property.

Solution (in JAVA):

Solution:
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.NoSuchElementException;

public class D {

    int N;
    ArrayList<Integer> x;

    private void solve() {
        N = nextInt();
        x = new ArrayList<>();
        for(int i = 0;i < N;i++) {
            x.add(nextInt());
        }

        Collections.sort(x);

        int[] ans = new int[3];
        int size = 0;
        for(int v : x) {
            for(int bit = 0;bit < 31;bit++) {

                int small = v - (1 << bit);
                int big = v + (1 << bit);

                int ind1 = Collections.binarySearch(x, small);
                int ind2 = Collections.binarySearch(x, big);

                if (ind1 >= 0 && ind2 >= 0 && size < 3) {
                    ans[0] = small;
                    ans[1] = v;
                    ans[2] = big;
                    size = 3;
                }

                if (ind1 >= 0 && ind2 < 0 && size < 2) {
                    ans[0] = small;
                    ans[1] = v;
                    ans[2] = -1;
                    size = 2;
                }

                if (ind1 < 0 && ind2 >= 0 && size < 2) {
                    ans[0] = v;
                    ans[1] = big;
                    ans[2] = -1;
                    size = 2;
                }
            }
        }

        if (size == 0) {
            out.println(1);
            out.println(x.get(0));
            return;
        }

        out.println(size);
        for(int i = 0;i < size;i++) {
            if (i != 0) {
                out.print(" ");
            }
            out.print(ans[i]);
        }
        out.println();

    }

    public static void main(String[] args) {
        out.flush();
        new D().solve();
        out.close();
    }

    /* Input */
    private static final InputStream in = System.in;
    private static final PrintWriter out = new PrintWriter(System.out);
    private final byte[] buffer = new byte[2048];
    private int p = 0;
    private int buflen = 0;

    private boolean hasNextByte() {
        if (p < buflen)
            return true;
        p = 0;
        try {
            buflen = in.read(buffer);
        } catch (IOException e) {
            e.printStackTrace();
        }
        if (buflen <= 0)
            return false;
        return true;
    }

    public boolean hasNext() {
        while (hasNextByte() && !isPrint(buffer[p])) {
            p++;
        }
        return hasNextByte();
    }

    private boolean isPrint(int ch) {
        if (ch >= '!' && ch <= '~')
            return true;
        return false;
    }

    private int nextByte() {
        if (!hasNextByte())
            return -1;
        return buffer[p++];
    }

    public String next() {
        if (!hasNext())
            throw new NoSuchElementException();
        StringBuilder sb = new StringBuilder();
        int b = -1;
        while (isPrint((b = nextByte()))) {
            sb.appendCodePoint(b);
        }
        return sb.toString();
    }

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

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

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