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 you help me for a minute ? 
 Person2:Sure , what I can do for you ? 
 Person1:        I'm try to write a letter to one of our clients , But I just don't know exactly what to say , I don't even know how to get started , I know I should write dear Mr . Mrs . or Ms . , but the problem is I don't know the name of contact person . 
 Person2:You can just put Dear Sir or Madam , officialese not personal , you can write to whom may concerned . 
 Person1:        OK , So I first thanks them for their business , I can say something like we are very grateful for your continue support , How is that ? 
 Person2:Good ! But also , write off the bed you want to tell them the reason of your writing , give them more reference . 
 Person1:        Like Regarding our new product line , we would like to announce a special price discount 
 Person2:Right , do you need them to respond ? 
 Person1:        Yes , the letter would have a survey inside , and they should complete it and return to our office . How should I write that ? 
 Person2:You can tell them " Please finding the enclosed customer service survey , else also , you can say Attach a customer survey . If you need resource it right away , you can tell them the urgent by saying Please return the survey without dely as soon as possible . Maye it more polite with this as early as convenience . 

formal