Unreal condition (past situation)

Situation 1: Last month your friends went to Australia on holiday. You didn’t know about this but it was your dream to visit Australia. So when you met your friends you said:

If I had known you went to Australia, I would have joined you.

But this is unreal now.

Situation 2: Your groupmate had some problems last week. But he didn’t tell you about them. So you say:

If you had addressed me, I could have helped you.

These are the examples of THIRD CONDITIONALS.