You are given a conversation between two people. 'Person1:' and 'Person2:' are used to separate their respective dialogues. You are required to assign a label 'formal' if there is an absence of emotion and a presence of questions anywhere within the conversation. If such pattern is not found assign the label 'informal'.
Q: Person1: You saved my life yesterday , Rachel . I can't believe I forgot to bring my wallet when we went to lunch with those clients .
Person2:It was a good thing I had enough on me .
Person1: Let me buy you lunch today to pay you back .
A:
informal