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:       Thanks a lot for having us . We had a good time .  
 Person2:I'm glad you came . You're welcome anytime .  
 Person1:        Thanks . By the way , tell your wife she throws a great party .  
 Person2:I will . See you later . 

informal