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 allow me to drive your car ?  
 Person2:No problem , but you've got to be careful .  
 Person1:        Surely I will .  
 Person2:Here's the key then . 

informal