There is a 3 lane road of length `n` that consists of `n + 1` points labeled from `0` to `n`. A frog starts at point `0` in the second lane and wants to jump to point `n`. However, there could be obstacles along the way.

You are given an array `obstacles` of length `n + 1` where each `obstacles[i]` (ranging from 0 to 3) describes an obstacle on the lane `obstacles[i]` at point `i`. If `obstacles[i] == 0`, there are no obstacles at point `i`. There will be at most one obstacle in the 3 lanes at each point.

- For example, if `obstacles[2] == 1`, then there is an obstacle on lane 1 at point 2.

The frog can only travel from point `i` to point `i + 1` on the same lane if there is not an obstacle on the lane at point `i + 1`. To avoid obstacles, the frog can also perform a side jump to jump to another lane (even if they are not adjacent) at the same point if there is no obstacle on the new lane.

- For example, the frog can jump from lane 3 at point 3 to lane 1 at point 3.

Return the minimum number of side jumps the frog needs to reach any lane at point n starting from lane `2` at point 0.

Note: There will be no obstacles on points `0` and `n`.

Example 1:

    Input: obstacles = [0,1,2,3,0]
    Output: 2
    Explanation: The optimal solution is shown by the arrows above. There are 2 side jumps (red arrows).
    Note that the frog can jump over obstacles only when making side jumps (as shown at point 2).

Example 2:

    Input: obstacles = [0,1,1,3,3,0]
    Output: 0
    Explanation: There are no obstacles on lane 2. No side jumps are required.

Example 3:

    Input: obstacles = [0,2,1,0,3,0]
    Output: 2
    Explanation: The optimal solution is shown by the arrows above. There are 2 side jumps.

Constraints:

- `obstacles.length == n + 1`
- `1 <= n <= 5 * 105`
- `0 <= obstacles[i] <= 3`
- `obstacles[0] == obstacles[n] == 0`