You will be given a definition of a task first, then some input of the task.
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'.

Person1: Thank you for coming to see me off .
Person2:Not at all .
Person1: If have time , I'll come again .
Person2:You're welcome at any time .
Person1: Thank you for your hospitality . I hope I didn't cause you too much trouble during my stay .
Person2:You're most welcome .
Person1: I'm afraid I have to go now . The plane will take off soon .
Person2:Call us as soon as you get home .
Output:
informal