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:       Here you are at last ! You're half an hour late , you know . 
 Person2:I'm awfully sorry to have kept you waiting for so long . 
 Person1:        What happened ? 
 Person2:My watch stopped and I didn't know . I certainly need to buy a better one . 

informal