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:       finally we're on board !  
 Person2:yes . It was so crowded . I'm worn-out . Let's find our seats .  
 Person1:        are they window seats or aisle seats ?  
 Person2:let me see ... yes , one window seat and one aisle seat .  
 Person1:        ok . But can I trade my seat with you ? I prefer the one near the window . I'm a terrible flyer . I always get airsick and can never relax until after I've landed .  
 Person2:that's fine . I'd like to be on the aisle anyway . It's easier to get in and out .  
 Person1:        thanks . Where shall we put our luggage ?  
 Person2:I think the smaller carry-on bag can go in the overhead compartment , and the others can go under the seat .  
 Person1:        good idea .  
 Person2:don't forget to keep the seat belt on .  
 Person1:        ok . Hope it's a pleasant trip .  
 Person2:yes !  
 Person1:        and no hijackers .  
 Person2:oh , you have too wild of an imagination . 

formal