class Solution:

# def peakIndexInMountainArray(self, A):

# """

# :type A: List[int]

# :rtype: int

# """

# low = 0

# higt = len(A)-1

# while low < higt:

# med = (low + higt) // 2

# if med == len(A)-1:

# return len(A)-1

# elif A[med-1] < A[med] and A[med] > A[med+1]:

# return med

# elif A[med-1] > A[med]:

# higt = med - 1

# else:

# low = med + 1

# return low

def peakIndexInMountainArray(self, A):

low, high = 0, len(A) - 1

while low <= high:

mid = (high - low) // 2 + low

if mid in (0, len(A) - 1):

return mid

elif A[mid] > A[mid - 1] and A[mid] > A[mid + 1]:

return mid

elif A[mid] < A[mid - 1]:

high = mid - 1

else:

low = mid + 1

return -1

print(Solution().peakIndexInMountainArray([1, 2, 3, 2, 1]))