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.util.*;
import java.lang.*;

public class Points
{
	public static void main(String[]args)
	{
		Scanner sc=new Scanner(System.in);
		int n=sc.nextInt();
		int m=sc.nextInt();
		int[]a=new int[n*2];
		int i;
		for( i=0;i<n*2;i++)
		{
			a[i]=sc.nextInt();
		}
		func(n,m,a);
	}

	static void func(int n,int m,int[]a)
	{
		int i,j,k=0;
		int[]arr=new int[m];
		//Arrays.fill(arr,0);
		for(i=1;i<=m;i++)
		{
			for(j=0;j<n*2;j=j+2)
			{
				if(i>=a[j]&&i<=a[j+1])
				{
					break;
				}
			}
			if(j>=n*2)
			{
				arr[k]=i;
				k++;
			}
		}
		System.out.print(k);
		System.out.println("");
		for(i=0;i<k;i++)
		{
			System.out.print(arr[i]+" ");
		}
	}
}