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:       Melissa ? I ’ d like to invite you to my wife ’ s birthday party . 
 Person2:Thanks , Frank . I ’ d love to come . When is it ? 
 Person1:        Her birthday is on the 9th . We ’ re going to have dinner at a Mexican restaurant , and then maybe go out dancing . 
 Person2:Sounds like fun . You can count me in ! Just give me directions to the restaurant . 

informal