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:       Then I'll take them . How much ?  
 Person2:$ 120.The small gift box is complementary .  
 Person1:        Here is $ 150.Keep the change .  
 Person2:Thank you ! Have a nice day !  
 Person1:        You too.Bye . 

informal