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:       Good morning and welcome . How can I help you ?  
 Person2:Could you tell me something about safety deposit box rental , please ? I need somewhere safe to keep some insurance documents ; I just simply don't feel comfortable keeping them at home or in the office .  
 Person1:        We have 3 different types of boxes . We usually rent for 1 year and the fee depends on the size and location of the box .  
 Person2:I think I'll go for the smallest , as it's just for documents . Will I be the only key holder ? I'd perhaps feel a little nervous if I knew someone else could have access to it at any time .  
 Person1:        You can have more than 1 key if you'd like , but we must have signature cards for each box .  
 Person2:That's great ; I can give an extra key to my wife . I feel perfectly comfortable with her having a key . Thanks for your help .  
 Person1:        If you have your ID and are willing to pay a year in advance , we can do that for you today , there is no need to wait .  
 Person2:OK , I'll take a small , for 1 year , in this branch , please . 

informal