Instructions: 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: Bob , did you see our supervisor ? I need him to sign this paper .
Person2:He is in his office , but you'd better choose your words carefully while talking to him .
Person1: What's up ?
Person2:Nothing . But he is in a bad mood today .
Person1: Thanks for the warning .
Person2:That's all right .
Output:
informal