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:       Hey ! I have a surprise for you .  
 Person2:What is it ?  
 Person1:        Open this card and read .  
 Person2:A trip to China for summer vacation . Wow ! What a wonderful surprise ! Thank you . This is the best surprise I've ever had . 

informal