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 , would you mind taking a picture for us ?  
 Person2:Of course not . Just tell me how to operate it .  
 Person1:        It's simple . Just press the button , like this .  
 Person2:I know . Hold your position and say cheese .  
 Person1:        Thank you . 

informal