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.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.Scanner;
public class Main {
	   
		public static void main (String args []) {
		Scanner sc = new Scanner(System.in);
		 int n=sc.nextInt();
		 int m=sc.nextInt();
		 int arr[]=new int[m+1]; int j=0;
		 while(n-->0) {
			 int l=sc.nextInt();
			 int r=sc.nextInt();
			
		  for(int i=l;i<=r;i++)
		  { 
			  arr[i]++;
			  
		  }
		}int arr2[]=new int[m+1];
		 int count=0;
		 for(int i=1;i<m+1;i++)
		 {
			 if(arr[i]==0) {
				 count++;
				 arr2[i]=i;
				 
				 }
		 }
		 System.out.println(count);
		 for(int i=1;i<m+1;i++)
		 {
			 if(arr[i]==0) {
				 System.out.print(arr2[i]+" ");
				 
				 }
		 }
		}
	
 }