Problem: You are given a set of n segments on the axis Ox, each segment has integer endpoints between 1 and m inclusive. Segments may intersect, overlap or even coincide with each other. Each segment is characterized by two integers l_i and r_i (1 ≤ l_i ≤ r_i ≤ m) — coordinates of the left and of the right endpoints. 

Consider all integer points between 1 and m inclusive. Your task is to print all such points that don't belong to any segment. The point x belongs to the segment [l; r] if and only if l ≤ x ≤ r.

Input

The first line of the input contains two integers n and m (1 ≤ n, m ≤ 100) — the number of segments and the upper bound for coordinates.

The next n lines contain two integers each l_i and r_i (1 ≤ l_i ≤ r_i ≤ m) — the endpoints of the i-th segment. Segments may intersect, overlap or even coincide with each other. Note, it is possible that l_i=r_i, i.e. a segment can degenerate to a point.

Output

In the first line print one integer k — the number of points that don't belong to any segment.

In the second line print exactly k integers in any order — the points that don't belong to any segment. All points you print should be distinct.

If there are no such points at all, print a single integer 0 in the first line and either leave the second line empty or do not print it at all.

Examples

Input

3 5
2 2
1 2
5 5


Output

2
3 4 


Input

1 7
1 7


Output

0

Note

In the first example the point 1 belongs to the second segment, the point 2 belongs to the first and the second segments and the point 5 belongs to the third segment. The points 3 and 4 do not belong to any segment.

In the second example all the points from 1 to 7 belong to the first segment.

Solution (in JAVA):

Solution:
import java.io.PrintWriter;
import java.util.*;

public class Main
{
	public static void main(String[] args) 
	{
		Scanner sc = new Scanner(System.in);
		PrintWriter out = new PrintWriter(System.out);
		
		int s = sc.nextInt();
		int len = sc.nextInt();
		int[] arr = new int[len+2];
		
		for(int i=0; i<s; i++)
		{
			int l = sc.nextInt();
			int r = sc.nextInt();
			arr[l]++;
			arr[r+1]--;
		}
		for(int i=1; i<arr.length; i++)
			arr[i] = arr[i-1]+arr[i];
		
		int count = 0;
		ArrayList<Integer> res = new ArrayList<Integer>();
		for(int i=1; i<= len; i++)
		{
			if(arr[i]==0)
			{
				count++;
				res.add(i);
			}
		}
		out.println(count);
		int k = 0; 
		while(k<res.size())
		{
			out.print(res.get(k)+ " ");
			k++;
		}
		out.close();
	}
}