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:       Hello , Jack.It ' s good of you to come . 
 Person2:The pleasure is mine.Happy birthday and many happy returns of the day ! 
 Person1:        Thank you , Jack.To be frank , I'd rather forget my birthday . 
 Person2:Don't be silly . 

informal