Read the following dialogue carefully and answer the questions!
 

Debby: Hi, good evening Debby.

Diana: Good evening, Diana.

Debby: What are you doing here?

Diana: Oh, I am waiting for my mom. We are going to have dinner together.

Debby: I am going to have dinner too.

Diana: Really? Do you want to join with us? My mom will be happy, I am sure.

Debby: Is it okay?

Diana: Of course. Come join with us.

Debby: As your wish.

(After for a while her mom came)

Mother: Hello, kiddos. Good evening.

Diana: Good evening, Mom. Would you mind if I ask Debby to join with us?

Mother: It is okay, Diana. Come! Get to the car!

Diana: Okay, Mom.

Debby: Thank you for allowing me to join.

Mother: My pleasure, kiddos.

1. How many persons in the dialogue?