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:       We will have a vacation next month . Why not have a tour ?  
 Person2:Good idea . Where shall we go ?  
 Person1:        What about going to Xi'an ?  
 Person2:Don't you think it is too far ?  
 Person1:        So what's your plan ?  
 Person2:What about going to Beijing ?  
 Person1:        So we'll compromise . We'll hit the Huangshan in Anti .  
 Person2:OK ! 

formal