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:       Operator , can you give me any information on the call I just received ?  
 Person2:I don ’ t know who placed the call . However , the call was from Toronto .  
 Person1:        Can you tell me the calling number , please ?  
 Person2:Sure . 416-790-1256 .  
 Person1:        Thank you .  
 Person2:You ’ re welcome . 

informal