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:       Bill , do you know when did the Chinese begin to celebrate Teachers ' Day ?  
 Person2:I know the Chinese teachers had their first festival in 1985 .  
 Person1:        So , it is the 27th Teachers ' Day .  
 Person2:What will you do on Teachers ' Day ?  
 Person1:        I am going to send Mr . Li some flowers . What about you ?  
 Person2:I intend to invite him to dinner . 

formal