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.awt.List;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.text.DecimalFormat;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.HashSet;
import java.util.InputMismatchException;
import java.util.Locale;
import java.util.Map;
import java.util.Set;
import java.util.TimeZone;

public class D {

	public static void main(String[] args) {
		Locale.setDefault(Locale.US);
		InputStream inputstream = System.in;
		OutputStream outputstream = System.out;
		FastReader in = new FastReader(inputstream);
		PrintWriter out = new PrintWriter(outputstream);
		TaskA solver = new TaskA();
		// int testcase = in.ni();
		for (int i = 0; i < 1; i++)
			solver.solve(i, in, out);
		out.close();

	}

}

class TaskA {

	public void solve(int testnumber, FastReader in, PrintWriter out) {
		int n = in.ni();
		int arr[] = in.iArr(n);

		Set<Long> map = new HashSet<>();

		for (int i = 0; i < n; i++) {
			map.add((long)arr[i]);
		}

		for (int i = 0; i < n; i++) {
			long temp = 1;
			for (int j = 0; j < 34; j++) {
				int current = arr[i];
				if (map.contains(current - temp)
						&& map.contains(current + temp)) {
					out.println("3");
					out.println((current - temp) + " " + (current) + " "
							+ (current + temp));
					return;
				}
				temp *= 2;
			}
		}
		for (int i = 0; i < n; i++) {
			long temp = 1;
			for (int j = 0; j < 34; j++) {
				int current = arr[i];
				if(map.contains(current - temp)){
					out.println("2");
					out.println((current - temp) + " " + (current));
					return;
				}
				if(map.contains(current + temp)){
					out.println("2");
					out.println((current) + " " + (current + temp));
					return;
				}
				temp *= 2;
			}
			
		}
		System.out.println(1);
		System.out.println(arr[0]);
	}
}

class FastReader {
	public InputStream stream;
	private byte[] buf = new byte[1024];
	private int curChar;
	private int numChars;
	private SpaceCharFilter filter;

	public FastReader(InputStream stream) {
		this.stream = stream;
	}

	public FastReader() {

	}

	public int read() {
		if (numChars == -1) {
			throw new InputMismatchException();
		}
		if (curChar >= numChars) {
			curChar = 0;
			try {
				numChars = stream.read(buf);
			} catch (IOException e) {
				throw new InputMismatchException();
			}
			if (numChars <= 0) {
				return -1;
			}
		}
		return buf[curChar++];
	}

	public int ni() {
		int c = read();
		while (isSpaceChar(c))
			c = read();
		int sgn = 1;
		if (c == '-') {
			sgn = -1;
			c = read();
		}
		int res = 0;
		do {
			if (c < '0' || c > '9') {
				throw new InputMismatchException();
			}
			res *= 10;
			res += c - '0';
			c = read();
		} while (!isSpaceChar(c));
		return res * sgn;
	}

	public String ns() {
		int c = read();
		while (isSpaceChar(c))
			c = read();
		StringBuilder res = new StringBuilder();
		do {
			res.appendCodePoint(c);
			c = read();
		} while (!isSpaceChar(c));
		return res.toString();
	}

	public boolean isSpaceChar(int c) {
		if (filter != null) {
			return filter.isSpaceChar(c);
		}
		return isWhitespace(c);
	}

	public static boolean isWhitespace(int c) {
		return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
	}

	public int[] iArr(int n) {
		int a[] = new int[n];
		for (int i = 0; i < n; i++) {
			a[i] = ni();
		}
		return a;
	}

	public String next() {
		return ns();
	}

	public interface SpaceCharFilter {
		public boolean isSpaceChar(int ch);
	}

}