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:       Mr . Green , I ’ d like to introduce you to Mr . Brown . 
 Person2:How do you do , Mr . Brown ? It ’ s a pleasure to get to know you . 
 Person1:        My pleasure , Mr . Green . I look forward to an excellent relationship with your company . 
 Person2:I propose a toast to the health of everyone here and to the success of our negotiation . 
 Person1:        Okay , let ’ s make a toast . 

informal