Definition: 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'.
Input:  Person1:       Could you do me a favor ? 
 Person2:What is it ? 
 Person1:        Could you possibly give me a lift home ? 
 Person2:All right . 
 Person1:        Are you sure ? I don't want to inconvenience you . 
 Person2:No problem . I'd be happy to . 
 Person1:        Thanks . I really appreciate it . Thanks so much . 

informal