There are four platforms in a railway station opening at different times: platform 1 at 5am, platform 2 at 6am, platform 3 at 7am, and platform 4 at 8...

There are four platforms in a railway station opening at different times: platform 1 at 5am, platform 2 at 6am, platform 3 at 7am, and platform 4 at 8am. Trains arrive at these platforms one by one with a one-hour gap between arrivals on the same platform. Multiple trains can arrive on a single platform but always with a one-hour gap.

Given the following conditions:

1. Train M is not the only train arriving on its platform.
2. Train D arrives immediately before train B on the same platform.
3. There is a one-hour gap between the arrivals of train G and train H on the same platform.
4. No train arrives after train C, which arrives at 6am on one of the platforms.
5. Train G and train B arrive at the same time, and train B arrives on platform 1.
6. The train that first arrives at 5am on platform 1 also arrives next at 7am on platform 3.
7. Train K arrives on platform 1 before train S, who arrives on platform 2.
8. Train H arrives on platform 2 at 7am.

Based on the above, the train arrival schedule is as follows:

Question: How many distinct trains arrive across all platforms (count each train only once)?