Problem: Long story short, shashlik is Miroslav's favorite food. Shashlik is prepared on several skewers simultaneously. There are two states for each skewer: initial and turned over.

This time Miroslav laid out n skewers parallel to each other, and enumerated them with consecutive integers from 1 to n in order from left to right. For better cooking, he puts them quite close to each other, so when he turns skewer number i, it leads to turning k closest skewers from each side of the skewer i, that is, skewers number i - k, i - k + 1, ..., i - 1, i + 1, ..., i + k - 1, i + k (if they exist). 

For example, let n = 6 and k = 1. When Miroslav turns skewer number 3, then skewers with numbers 2, 3, and 4 will come up turned over. If after that he turns skewer number 1, then skewers number 1, 3, and 4 will be turned over, while skewer number 2 will be in the initial position (because it is turned again).

As we said before, the art of cooking requires perfect timing, so Miroslav wants to turn over all n skewers with the minimal possible number of actions. For example, for the above example n = 6 and k = 1, two turnings are sufficient: he can turn over skewers number 2 and 5.

Help Miroslav turn over all n skewers.

Input

The first line contains two integers n and k (1 ≤ n ≤ 1000, 0 ≤ k ≤ 1000) — the number of skewers and the number of skewers from each side that are turned in one step.

Output

The first line should contain integer l — the minimum number of actions needed by Miroslav to turn over all n skewers. After than print l integers from 1 to n denoting the number of the skewer that is to be turned over at the corresponding step.

Examples

Input

7 2


Output

2
1 6 


Input

5 1


Output

2
1 4 

Note

In the first example the first operation turns over skewers 1, 2 and 3, the second operation turns over skewers 4, 5, 6 and 7.

In the second example it is also correct to turn over skewers 2 and 5, but turning skewers 2 and 4, or 1 and 5 are incorrect solutions because the skewer 3 is in the initial state after these operations.

Solution (in JAVA):

Solution:
//package Contest507;

import java.io.PrintWriter;
import java.util.Scanner;

public class M507B {
    public static Scanner enter = new Scanner(System.in);
    public static PrintWriter out = new PrintWriter(System.out);
    public static void main(String[] args) {
        int n=enter.nextInt();
        int k=enter.nextInt();
        if(k==0){
            out.println(n);
            for (int i = 1; i <=n ; i++) {
                out.println(i);
            }
            out.close();
        }
        else if(n<=k+1){
            out.println(1);
            out.println(n);
            out.close();
        }
        else if(n<=2*k+1){
            out.println(1);
            out.println(k+1);
            out.close();
        }
        else{
            int tmp=n%(2*k+1);
            if(tmp==0){
                out.println(n/(2*k+1));
                for (int i = k+1; i <=n ; i+=2*k+1) {
                    out.println(i);
                }
                out.close();
            }
            else if(tmp<=k){
                out.println((n-2*k-tmp-1)/(2*k+1)+2);
                out.println(1);
                for (int i =2*k+2; i <=n ; i+=2*k+1) {
                    out.println(i);
                }
                out.close();
            }
            else{
                out.println(n/(2*k+1)+1);
                out.println(tmp-k);
                for (int i = tmp+1+k; i <=n ; i+=2*k+1) {
                    out.println(i);
                }
                out.close();
            }
        }
    }
}