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:       Who ’ s this ? your girl-friend ?  
 Person2:No , it ’ s my sister .  
 Person1:        How old is she ?  
 Person2:She ’ s 18 .  
 Person1:        She is tall ?  
 Person2:Yes , she is .  
 Person1:        And she is thin , isn ’ t she ?  
 Person2:Well , just a little thin . 

formal