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:       Excuse me , I bought this sweater yesterday . But when I got home and tried it on , I found it ’ s too small .  
 Person2:Do you have the receipt with you ?  
 Person1:        Yes , here you are .  
 Person2:Thank you . Do you want your money back ?  
 Person1:        No , can I exchange it for a bigger one ?  
 Person2:I am afraid this is the biggest size we have .  
 Person1:        Oh , that's too bad .  
 Person2:Maybe you would like to try this one with the willow pattern . The price is the same and it's bigger . 

formal