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:       What do you think of doctor Thompson ?  
 Person2:I feel confident of his ability to cure my daughter's disease .  
 Person1:        How can you be so sure ?  
 Person2:I can tell from the way he spoke to us .  
 Person1:        Never believe his words . 

formal