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:       Would you like to stretch your legs ? 
 Person2:Why not ? 
 Person1:        Let's get a soft drink . 
 Person2:Do we have enough time ? 
 Person1:        Yes , we do . 
 Person2:The performance is excellent . 
 Person1:        It's a new concert hall and the acoustics are great . 
 Person2:I couldn't agree more . 
 Person1:        Is this your first time to come to a symphony concert ? 
 Person2:Yes , it is . 
 Person1:        Do you have concert halls in your city ? 
 Person2:Yes , but it's much smaller . 
 Person1:        Well , we'd better get back to our seats . It's about to start . 
 Person2:OK . 

informal