A month's schedule lists n shift codes in order. A shift is a night shift when its code is odd. Count how many contiguous blocks of the schedule contain exactly k night shifts (odd codes).
Input format
Line 1: two integers n and k.
Line 2: n space-separated non-negative integers, the shift codes in order.
Output format
A single integer: the number of contiguous subarrays containing exactly k odd values.
Constraints
- 1 ≤ n ≤ 100000
- 0 ≤ k ≤ n
- 0 ≤ each shift code ≤ 1000000000