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:       Are you free this evening , Li ?  
 Person2:I ’ m afraid I ’ m busy tonight . I ’ m having dinner with friends .  
 Person1:        What a pity . I wanted to go for a drink with you .  
 Person2:What about tomorrow ? Are you doing anything tomorrow ?  
 Person1:        No , I haven ’ t got any plans .  
 Person2:Shall we go out tomorrow then ?  
 Person1:        Why not ? Sounds good to me . 

informal