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:       I think Andy's party will be fun .  
 Person2:Yeah , I think so . Oh , by the way , I need to ask you something .  
 Person1:        What's that ?  
 Person2:Could I get back the sweater you borrowed ?  
 Person1:        Sure . Oh , that reminds me . Could I borrow your black leather boots ?  
 Person2:My boots ? Er ... Sure , ok . 

formal