class Solution:
    def decrease(self, nums):
        true = 1
        for i in range(len(nums) -1):
            if nums[i] > nums[i+1] and nums[i] != nums[i+1]:
                true += 1

        if true == len(nums):
            return True
        else:
            return False

    def increase(self, nums):
        true = 1
        for i in range(len(nums) -1):
            if nums[i] < nums[i+1] and nums[i] != nums[i+1]:
                true += 1

        if true == len(nums):
            return True
        else:
            return False

    def solve(self, nums):
        # Write your code here

        d = self.decrease(nums)
        i = self.increase(nums)

        if len(nums) == 0:
            return True

        if d == True or i == True:
            return True
        else:
            return False