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:       It's very thoughtful of you to invite me to your wedding .  
 Person2:How can I forget my old friend ?  
 Person1:        My best wishes to you and the bride !  
 Person2:Thank you very much . 

informal