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:       Happy birthday , Ms . Lin . Here is a present for you .  
 Person2:Oh , thank you ! It's very kind of you . Ah , it is a porcelain vase .  
 Person1:        I hope you like it .  
 Person2:Yes , it is lovely . I have been expecting something like this for a long time . Thanks ever so much .  
 Person1:        I am glad you like it . 

informal