spoj#UCBINTI. Sequence
Sequence
We say that an integer sequence a1, a2, ... , an is k-even if the sum of any k consecutive terms of the sequence is even.
For a given sequence we would like to find out how many of its terms need to be changed so that the sequence becomes k-even.
Input
The first line of input contains two integers n and k (1 ≤ k ≤ n ≤ 106). The second line contains a sequence composed of n integers a1, a2, ... , an. For each of the ai's it holds that 0 ≤ ai ≤ 109.
Output
The only line of output should hold one integer: the minimum number of terms of the sequence that need to be changed so that it becomes k-even.
Example
Input: 8 3 1 2 3 4 5 6 7 8</p>Output: 3
Input: 8 3 2 4 2 4 2 4 2 4 Output: 0