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:       do you have any plans for Friday night ?  
 Person2:I don't think so . Why ?  
 Person1:        well , my hosue-mates and I are having a house-warming party . Would you like to come ?  
 Person2:sure . Would it be alright if I brought a few friends ?  
 Person1:        the more , the merrier !  
 Person2:will there be a lot of people there ?  
 Person1:        I sure hope so . We've each invited about 10 people .  
 Person2:who else is going to be there ?  
 Person1:        I'm inviting my friends from work , you , my sister , and a few friends from school .  
 Person2:I know your sister . She's very nice .  
 Person1:        don't worry.You won't be sitting there by yourself .  
 Person2:what time is it going to start ?  
 Person1:        most people are working Friday night , so it's going to start around 9 pm .  
 Person2:should I bring anything ?  
 Person1:        we'll have beer and snacks , but if you want to bring a bottle of wine , that'd be great .  
 Person2:I could also bring some music if you want . I've got loads of songs on my new iPod .  
 Person1:        that'd be great . I'll see you then ! 

informal