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 . Could you please take a picture of us with this camera ?  
 Person2:Sure . Which button do I press to shoot ?  
 Person1:        This one .  
 Person2:Do I have to focus it ?  
 Person1:        No , this is a focus-free camera . All you have to do is point and press the button .  
 Person2:All right . Say cheese ! 

informal