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:
import javax.swing.text.MutableAttributeSet;
import java.util.*;
import java.io.*;


public class Main{

    public static void main(String[] args) throws IOException{
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        PrintWriter pw=new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.out)));
        StringTokenizer st=new StringTokenizer(br.readLine());
        int n=Integer.parseInt(st.nextToken());
        int k=Integer.parseInt(st.nextToken());

        int times=2*k+1;
        if(n%times==0){
            int start=k+1;
            int ans=n/times;
            StringBuilder str=new StringBuilder("");
            for(int i=1;i<=ans;i++){
                str.append(start+" ");
                start+=times;
            }
            pw.println(ans);
            pw.println(str);
        }else if(n%times>=k+1){
            int ans=n/times+1;
            StringBuilder str=new StringBuilder("");
            int start=k+1;
            for(int i=1;i<=ans;i++){
                str.append(start+" ");
                start+=times;
            }
            pw.println(ans);
            pw.println(str);
        }else {
            int ans=n/times-1;
            int rem=(n%times);
            int start=rem/2+1;
            StringBuilder str=new StringBuilder("");
            str.append(start+" ");
            start+=times;
            for(int i=0;i<=ans;i++){
                str.append(start+" ");
                start+=times;
            }
            if(ans==-1){
                pw.println("1");
                pw.println(rem/2+1);
            }else {
                pw.println(ans+2);
                pw.println(str);
            }
        }


        pw.close();
    }
}