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.util.*;
import java.io.*;

public class D {

	static final boolean stdin = true;
	static final String filename = "";
	static FastScanner br;
	static PrintWriter pw;

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

		if (stdin) {
			br = new FastScanner();
			pw = new PrintWriter(new OutputStreamWriter(System.out));
		} else {
			br = new FastScanner(filename + ".in");
			pw = new PrintWriter(new FileWriter(filename + ".out"));
		}

		Solver solver = new Solver();
		solver.solve(br, pw);
	}

	static class Solver {
		static long mod = (long) (1e10);

		public void solve(FastScanner br, PrintWriter pw) throws IOException {
			int n = br.ni();
			Integer[] in = br.nIa(n);
			TreeSet<Integer> ts = new TreeSet<Integer>();
			for (int i = 0; i < n; i++) {
				ts.add(in[i]);
			}
			String twoSol = "";
			for (int i = 0; i <= 30; i++) {
				for (int j : in) {
					if (ts.contains(j + (int) Math.pow(2, i))) {
						if (ts.contains(j - (int) Math.pow(2, i))) {
							pw.println(3);
							pw.println(j + " " + (j + (int) Math.pow(2, i)) + " " + (j - (int) Math.pow(2, i)));
							pw.close();
							System.exit(0);
						}else{
							twoSol = (j + " " + (j + (int) Math.pow(2, i)));
						}
					}
				}
			}
			if (twoSol.isEmpty()) {
				pw.println(1);
				pw.println(in[0]);
			} else {
				pw.println(2);
				pw.println(twoSol);
			}
			pw.close();
		}

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

		static long lcm(long a, long b) {
			return a * (b / gcd(a, b));
		}

		static long pow(long a, long b) {
			if (b == 0)
				return 1L;
			long val = pow(a, b / 2);
			if (b % 2 == 0)
				return val * val % mod;
			else
				return val * val % mod * a % mod;
		}

	}

	static class Point implements Comparable<Point> {
		int a;
		int b;

		Point(int a, int b) {
			this.a = a;
			this.b = b;
		}

		@Override
		public int compareTo(Point o) {
			return this.a - o.a;
		}

	}

	public static class FastScanner {
		BufferedReader br;
		StringTokenizer st;

		public FastScanner(String s) {
			try {
				br = new BufferedReader(new FileReader(s));
			} catch (FileNotFoundException e) {
				e.printStackTrace();
			}
		}

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

		ArrayList<Integer>[] ng(int n, int e) {
			ArrayList<Integer>[] adj = new ArrayList[n];
			for (int i = 0; i < n; i++) {
				adj[i] = new ArrayList<Integer>();
			}
			for (int i = 0; i < e; i++) {
				int a = ni() - 1;
				int b = ni() - 1;
				adj[a].add(b);
				adj[b].add(a);
			}
			return adj;
		}

		Integer[] nIa(int n) {
			Integer[] arr = new Integer[n];
			for (int i = 0; i < n; i++) {
				arr[i] = ni();
			}
			return arr;
		}

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

		Long[] nLa(int n) {
			Long[] arr = new Long[n];
			for (int i = 0; i < n; i++) {
				arr[i] = nl();
			}
			return arr;
		}

		long[] nla(int n) {
			long[] arr = new long[n];
			for (int i = 0; i < n; i++) {
				arr[i] = nl();
			}
			return arr;
		}

		String[] nsa(int n) {
			String[] arr = new String[n];
			for (int i = 0; i < n; i++) {
				arr[i] = nt();
			}
			return arr;
		}

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

		int ni() {
			return Integer.parseInt(nt());
		}

		long nl() {
			return Long.parseLong(nt());
		}

		double nd() {
			return Double.parseDouble(nt());
		}

	}
}