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:       Are you in favor of having a trip during the spring break ? 
 Person2:This is just what I have in mind.Where are you planning to go ? 
 Person1:        How about the Yellow Mountains ? 
 Person2:Good idea ! 

informal