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:       Would you like to come out with me tonight ?  
 Person2:Sorry , I can ’ t .  
 Person1:        Tomorrow night , then ?  
 Person2:I ’ d like to . But I ’ m afraid I can ’ t .  
 Person1:        I was wondering if you like to go to the theatre then .  
 Person2:That sounds great .  
 Person1:        Ok . How about give me a ring , then ?  
 Person2:No . I ’ d better not .  
 Person1:        Why not ?  
 Person2:Because I don ’ t think my husband would like it . Thank you for inviting me anyway . 

formal