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:       If I wanted to rent a van , how much would it cost ? 
 Person2:Let's see . That would be ¥ 160 a day a mile . 
 Person1:        That sounds OK . I'll need it from the 10th to the 14th . 
 Person2:Do you have a valid license ? 
 Person1:        Yeah . Here . 
 Person2:Fine . Now complete this form and sign your name at the bottom . 

informal