class Solution:
    def massage(nums):
        if len(nums) == 0:
            return 0
        elif len(nums) == 1:
            return nums[0]
        elif len(nums) == 2:
            return max(nums[0], nums[1])
        else:
            beforeyes = nums[0]
            yesday = nums[1]
            now = 0
            for i in range(2,len(nums)-1):
                now = max(nums[i] + beforeyes, yesday)
                beforeyes = yesday
                yesday = now
            return max(nums[len(nums)-1] + beforeyes, yesday)

s = Solution
n = [2,1,1,2]
print(s.massage(n))