Design a hit counter which counts the number of hits received in the past 5 minutes (300 seconds).

• void hit(int timestamp) — records a hit at given timestamp (in seconds).
• int getHits(int timestamp) — returns the number of hits in the past 300 seconds.

Each function will be called with strictly increasing timestamp values.

Example:

hit(1), hit(2), hit(3), getHits(4)→3, hit(300), getHits(300)→4, getHits(301)→3