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:       The sun is shining .  
 Person2:But there're some mare's tails .  
 Person1:        That's the sign of wind .  
 Person2:Oh , really , I thought it was a sign of rain . 

informal