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:       Hello ? 
 Person2:Hello ? 
 Person1:        Can I speak to Li Hong , please ? 
 Person2:Speaking . 
 Person1:        Hi , Li Hong.This is Alice . 
 Person2:Hi , Alice.How are you ? 
 Person1:        Not bad.Li Hong , I am sorry that I can ’ t go to see Mrs.Brown with you tomorrow morning.My mother is ill . I must take care of her . 
 Person2:I ’ m sorry to hear that.You ’ d better stay at home.After all , we can visit Mrs.Brown later 
 Person1:        OK.Bye - bye . 
 Person2:Bye . 

informal