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 java.util.List;
import java.util.ArrayList;
import java.util.Scanner;

public class MainCoock {
    public static void main(String[] args) {
        int input[] = getInputData();
        int n = input[0];
        int k = input[1];

        int block = k * 2 + 1;
        int rotateCount = (int) Math.floor(n / block);
        int rotateEnd = n - rotateCount * block;
        int curPosRotate = k + 1;
        if (k == 0) {
            curPosRotate = 1;
        }

        if (rotateEnd != 0 & rotateEnd <= k) {
            curPosRotate -= k + 1 - rotateEnd;
        }

        int count = 0; //  счетчик переворотов
        List<Integer> listRotate = new ArrayList<>();

        for (; curPosRotate <= n; curPosRotate += block) {
            count++;
            listRotate.add(curPosRotate);
        }

        System.out.println(count);
        for (int i = 0; i < listRotate.size(); i++) {
            System.out.print(listRotate.get(i) + " ");
        }
    }

    private static int[] getInputData() {
        int[] inputData = new int[2];

        Scanner sc = new Scanner(System.in);
        if (sc.hasNext()) {
            String[] inputLine = sc.nextLine().split(" ");

            for (int i = 0; i < inputLine.length; i++) {
                inputData[i] = Integer.valueOf(inputLine[i]);
            }
        }
        return inputData;
    }
}