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.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.HashSet;
import java.util.StringTokenizer;

public class Main3 {
	
	static boolean canAdd(HashSet<Integer> set, int n) 
	{
		lop: for(int i : set)
		{
			for(int j = 0; j <= 30; j++)
				if(Math.abs(n-i) == 1l<<j)
					continue lop;
			return false;
		}
		return true;
	}
	
	public static void main(String[] args) throws IOException 
	{
		Scanner sc = new Scanner(System.in);
//		Scanner sc = new Scanner("out");
		int n = sc.nextInt();
		HashSet<Integer> set = new HashSet<Integer>();
		int[] a = sc.nextIntArr();
		for (int i = 0; i < n; i++) 
			set.add(a[i]);
		HashSet<Integer> res = new HashSet<Integer>();
		for (int i = 0; i < a.length; i++)
		{
			HashSet<Integer> curSet = new HashSet<Integer>();
			curSet.add(a[i]);
			for(int j = 0 ; j <= 30;j++)
			{
				int cur = 1<<j;
				if(set.contains(a[i] + cur) && canAdd(curSet, a[i]+cur))
					curSet.add(a[i]+cur);
				cur*=-1;
				if(set.contains(a[i] + cur) && canAdd(curSet, a[i]+cur))
					curSet.add(a[i]+cur);		
			}
			if(curSet.size() > res.size())
				res = curSet;
		}
		System.out.println(res.size());
		StringBuilder sb = new StringBuilder();
		for(int i : res)
			sb.append(i+" ");
		System.out.println(sb);
	}
	
	static class Scanner 
	{
		StringTokenizer st;
		BufferedReader br;
		public Scanner(InputStream s){	br = new BufferedReader(new InputStreamReader(s));}
		public Scanner(String s) throws FileNotFoundException {br = new BufferedReader(new FileReader(s));}
		public String next() throws IOException 
		{
			while (st == null || !st.hasMoreTokens()) 
				st = new StringTokenizer(br.readLine());
			return st.nextToken();
		}
		public int nextInt() throws IOException {return Integer.parseInt(next());}
		public String nextLine() throws IOException {return br.readLine();}		
		public long nextLong() throws IOException {return Long.parseLong(next());}		
		public double nextDouble() throws IOException {return Double.parseDouble(next());}	
		public char nextChar() throws IOException{return next().charAt(0);}
		public boolean ready() throws IOException {return br.ready();}
		public int[] nextIntArr() throws IOException{
			st = new StringTokenizer(br.readLine());
			int[] res = new int[st.countTokens()];
			for (int i = 0; i < res.length; i++)
				res[i] = nextInt();
			return res;
		}
		public char[] nextCharArr() throws IOException{
			st = new StringTokenizer(br.readLine());
			char[] res = new char[st.countTokens()];
			for (int i = 0; i < res.length; i++) 
				res[i] = nextChar();
			return res;
		}
	}

}