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 HelloWorld{

     public static void main(String[] args){
        //System.out.println("Hello World");
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int u = sc.nextInt();
        //int arr[n*2] = new int[n*2];
        int ans[] = new int[u];
        for(int i=0;i<n;i++){
            int start = sc.nextInt();
            int stop = sc.nextInt();
            //System.out.println(start +" " + stop);
            for(int l=start-1;l<stop;l++){
                ans[l]=1;
            }
            
        }
        int count=0;
        for(int x:ans){
            if(x==0){
                count++;
                
            }
        }
        System.out.println(count);
        for(int x=0;x<u;x++){
            if(ans[x]==0){
                System.out.print((x+1) + " ");
                
            }
        }
        
        /*for(int i=0;i<u;i++){
            ans[i] = 0;
        }
        for()*/
        
     }
}