How Many Drops?

The rollercoaster's altitude log shows every moment of the ride — count the stomach-drops! 🎢

You get the altitudes as nums. Print how many times the value goes DOWN from one reading to the next.

Example:

Input: nums = [10, 20, 15, 25, 5] Output: 2

10→20 rises, 20→15 drops (1), 15→25 rises, 25→5 drops (2) — that's 2 drops total.