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 PYTHON3):

Solution:
n, k = map(int, input().split())
a = 2 * k + 1
b = k + 1
flag = False
if n % (2 * k + 1) >= k + 1 or n % (2 * k + 1) == 0:
    ans = n // (2 * k + 1)
    if n % (2 * k + 1) > 0:
        ans += 1
        flag = True
    print(ans)
    i = b
    g = i + k
    ans_c = 0
    while g <= n and ans_c < ans:
        print(i, end=' ')
        ans_c += 1
        g += 2 * k + 1
        i += 2 * k + 1
    if g != n and i <= n:
        print(i)
else:
    ans = 0
    if (n - k - 1) % (2 * k + 1) != 0 and n > k + 1:
        ans += (n - k - 1) // (2 * k + 1) + 1
    elif (n - k - 1) % (2 * k + 1) == 0:
        ans += (n - k - 1) // (2 * k + 1)
    ans += 1
    print(ans)
    print(1, end=' ')
    i = 1
    g = k + 1
    ans_c = 1
    while g <= n and ans_c < ans:
        ans_c += 1
        g += 2 * k + 1
        i += 2 * k + 1          
        print(i, end=' ')
    if g != n and i <= n and ans_c < ans:
        print(i)