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:       Is this the foreign exchange department ?  
 Person2:Yes , can I help you ?  
 Person1:        I need some US Dollars .  
 Person2:What kind of currency have you got ?  
 Person1:        RIB . By the way , what is the exchange rate today ?  
 Person2:One US Dollars in cash is equivalent t0 7.9 Yuan .  
 Person1:        And I want to change 4000 Yuan .  
 Person2:Minus the fee . Here are your dollars . Please sign here .  
 Person1:        OK , thank you . 

formal