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:       Do you know Mark ? 
 Person2:Yeah ! He is a nice guy . He is very helpful and always bends over backward to help those who are in need of help . 
 Person1:        Can you introduce him to me ? 
 Person2:Sure . 

informal