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

        i = self.inc(nums)
        d = self.dec(nums)

        if len(nums) == 1 or len(nums) == 0:
            return True

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


    def inc(self, nums):
        t = 1

        for i in range(len(nums) - 1):
            if nums[i] < nums[i+1]:
                t += 1

        if t == len(nums):
            return True


    def dec(self, nums):
        t = 1

        for i in range(len(nums) - 1):
            if nums[i] > nums[i+1]:
                t += 1

        if t == len(nums):
            return True
```