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:       Bob , did you see our supervisor ? I need him to sign this paper . 
 Person2:He is in his office , but you'd better choose your words carefully while talking to him . 
 Person1:        What's up ? 
 Person2:Nothing . But he is in a bad mood today . 
 Person1:        Thanks for the warning . 
 Person2:That's all right . 

informal