How many people are there in the dialogue?

M: Kate, look! The passengers are coming from the plane, and there’s Susan.
W: Which one?
M: The tall one next to the window.
W: The one with the suitcase?
M: No. The one with the package under her arm.
W: Oh, yes! That’s Susan!
M: Hello, Susan! How was the trip?
W: Fine. It was a very good flight.