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:       I got the job you recommended me for last week .  
 Person2:That's great ! Congratulations .  
 Person1:        I really don't know how I can thank you enough .  
 Person2:Oh , it's my pleasure . After all , you are very qualified for the position .  
 Person1:        Thank you very much indeed.You helped me rebuild my self-confidence .  
 Person2:Don't mention it.You ' re always been good.What do you say we go out to celebrate ?  
 Person1:        That would be great . 

informal