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:       Excuse me , are you Dr . Smith ?  
 Person2:Yes I am . And you ...  
 Person1:        I'm David , Joanna's husband . She has to be at work late today . So she asked me to pick you up here .  
 Person2:So nice to meet you , David . Call me Bill . It's very nice of you to come here .  
 Person1:        My pleasure . 

informal