Fast MS SQL solution
\nSELECT actor_id, director_id\nFROM ActorDirector\nGROUP BY actor_id, director_id\nHaving count(distinct timestamp) >= 3\n
```\nSELECT actor_id, director_id\nFROM ActorDirector\nGROUP BY actor_id, director_id\nHaving count(distinct timestamp) >= 3\n```
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