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'.

[Q]: Person1: What do you plan to do for your birthday ?
Person2:I want to have a picnic with my friends , Mum .
Person1: How about a party at home ? That way we can get together and celebrate it .
Person2:OK , Mum . I'll invite my friends home .
[A]: informal

[Q]: Person1: Good afternoon , everyone . The experiment is to start at 3 . Have you gone through the instructions ?
Person2:Yes , sir .
Person1: Ok , now some points for attention . First of all , pay attention to safety ... Now , sign your names on the lab record , and after that you can start . If there is any question , just let me know .
Person2:Excuse me , sir . This air compressor doesn't work .
Person1: Have you turned it on ?
Person2:Yes , I have .
Person1: Ok , I will get you another one .
Person2:Thank you .
[A]: formal

[Q]: Person1: What can I do for you ?
Person2:Yes . There is something wrong with my watch . It stopped several hours ago .
Person1: Let me have a look . Oh , the watch ' s battery is worn down .
Person2:How much is a battery ?
Person1: $ 50 .
Person2:How long will it last ?
Person1: About 2 years .
Person2:Here is the money .
[A]:
formal