
Changing direction

You are given a sequence of integers. Your task in this mission is to find, how many times the sorting direction was changed in the given sequence. If the elements are equal - the previous sorting direction remains the same, if the sequence starts from the same elements - look for the next different to determine the sorting direction.
Let's look at the scheme:
There are three sorting directions:
- on the chunk 1, 2, 2 - up (increasing);
- on the chunk 2, 1 - down (decreasing);
- and on the chunk 1, 2, 2 - up again.
Input: List of integers (int).
Output: An integer (int).
Examples:
assert changing_direction([1, 2, 3, 4, 5]) == 0 assert changing_direction([1, 2, 3, 2, 1]) == 1 assert changing_direction([1, 2, 2, 1, 2, 2]) == 2
Preconditions:
- the sequence is non-empty;
- the elements are positive integers.