Complete the dialogue, using must / mustn't.
A: It's dangerous to go hiking there. You (1)________ tell someone where you are going.
B: Yes. And I (2) ________ take a warm coat. it's very cold there.
A: Right. But you (3) ________ bring any heavy of unnecessary things with you.
B: OK, and I (4) ________ take a mobile phone. It's very important.
A: And you (5) ________ forget to bring a compass.