You may recall that an array `arr` is a mountain array if and only if:

- `arr.length >= 3`
- There exists some index `i` (0-indexed) with `0 < i < arr.length - 1` such that:
  - `arr[0] < arr[1] < ... < arr[i - 1] < arr[i]`
  - `arr[i] > arr[i + 1] > ... > arr[arr.length - 1]`

Given an integer array `nums`​​​, return the minimum number of elements to remove to make `nums​​​` a mountain array.

Example 1:

    Input: nums = [1,3,1]
    Output: 0
    Explanation: The array itself is a mountain array so we do not need to remove any elements.

Example 2:

    Input: nums = [2,1,1,5,6,2,3,1]
    Output: 3
    Explanation: One solution is to remove the elements at indices 0, 1, and 5, making the array nums = [1,5,6,3,1].

Constraints:

- `3 <= nums.length <= 1000`
- `1 <= nums[i] <= 109`
- It is guaranteed that you can make a mountain array out of `nums`.