Instructions: 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: Do you know what the BBS is ?
Person2:Sure .
Person1: Tell me then .
Person2:BBS means Bulletin Board Service .
Person1: Oh , I see , but what's it used for ?
Person2:A lot of things !
Person1: Tell me in details .
Person2:Okay . BBS , an online service , offers a wide variety of online games , files , one-on-one chat , message areas , private mail , and participate forums .
Person1: Oh , that's great . I want to try later .
Person2:Why not ?
Output:
informal