class Solution:
    def numOfSubarrays(self, arr: List[int]) -> int:
      presum = [0] * len(arr)
      pre = 0
      for i,v in enumerate(arr):
        presum[i] = pre + v
        pre = presum[i]
      presum = [0] + presum
      
      cnt1 = 0
      cnt2 = 0
      res = 0
      for i in presum:
        if i % 2 == 0:
          cnt2 += 1
          res += cnt1
        else:
          cnt1 += 1
          res += cnt2
      return res % (10**9+7)