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.*;
public class Main
{
	public static void main(String[] args)
	{
	    Scanner sc=new Scanner(System.in);
	    int n=sc.nextInt();
	    int m=sc.nextInt();
	    int a[]=new int [m+1];
	    for(int i=0;i<m;i++)
	    {
	        a[i]=0;
	    }
	    int c=0;
	    
	    for(int i=0;i<n;i++)
	    {
	        int s=sc.nextInt();
	        int e=sc.nextInt();
	        if(e>a[s])
	       {
	          a[s]=e;
	           
	       }
	    }
	    int pos=1;
	    int pp=1;
	    ArrayList<Integer> list=new ArrayList<>();
	    while(pos<=m)
	    {
	        if(a[pos]==0&&pos>=pp)
	        {
	            c++;
	            list.add(pos);
	           
	        }
	        else
	        {
	            if(a[pos]>pp)
	            pp=a[pos]+1;
	        }
	        
	        pos++;
	        
	    }
	    System.out.println(c);
        
        for(int i=0;i<list.size();i++)
	    System.out.print(list.get(i)+" ");
	    }
	    
	        
	    
		
	
}