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:

| Platform | 5am | 6am | 7am | 8am |
|------------|-----|-----|-----|-----|
| Platform 1 | K | C | D | B |
| Platform 2 | --- | S | H | G |
| Platform 3 | --- | K | M | --- |
| Platform 4 | --- | --- | --- | C |

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

Question

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:

| Platform   | 5am | 6am | 7am | 8am |
|------------|-----|-----|-----|-----|
| Platform 1 | K   | C   | D   | B   |
| Platform 2 | --- | S   | H   | G   |
| Platform 3 | --- | K   | M   | --- |
| Platform 4 | --- | --- | --- | C   |

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

Accepted Answer

**Solution:**

1. From the given schedule, list all trains appearing on the platforms:
   - Platform 1: K, C, D, B
   - Platform 2: S, H, G
   - Platform 3: K, M
   - Platform 4: C

2. Combine all trains and count unique ones:
   - K (appears twice but counted once)
   - C (appears twice but counted once)
   - D
   - B
   - S
   - H
   - G
   - M

3. Total distinct trains = 8

**Answer:** Eight

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