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:       Mr.Martin , we're on arrival . 
 Person2:It's nice of you to see my off at the airport . Thank you very much . 
 Person1:        We'll miss you . I hope we'll keep in touch . 
 Person2:Sure . You've given a great help to me in the past days . 
 Person1:        It's my pleasure . We hope you'll visit Beijing again . 
 Person2:Certainly . I'll be glad to . 
 Person1:        It's almost time to get aboard . 
 Person2:Yes , we should go . Thank you very much . Goodbye ! 
 Person1:        Bye bye ! Have a pleasant journey ! 

informal