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class Solution:
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    def validMountainArray(self, arr: List[int]) -> bool:
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        if len(arr) <= 2 or max(arr) == arr[0] or max(arr) == arr[len(arr) - 1]:
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            return False
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        f = True
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        for i in range(len(arr) - 1):
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            if f and arr[i] >= arr[i + 1]:
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                f = False
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            if not f and arr[i] <= arr[i + 1]:
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                return False
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        return True