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:       Can I help you sir , what do you need ?  
 Person2:I need a packet of cigarettes please .  
 Person1:        Of course sir , no problem .  
 Person2:Thanks . 

informal