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:       Hello , this is Chen Kun . I am booked on flight LJ88 for Barcelona on Jan . 19th .  
 Person2:Hold on please ... Yes , you are booked already .  
 Person1:        Now I am afraid I can't get to the airport on that day . I want to change my flight for the 21st.Is that all right ?  
 Person2:I am sorry.Flight LJ88 0n that day is full . What about 22 ?  
 Person1:        Fine.Thank you so much . 

informal