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 . Wilson . I'm very glad we reached the agreement at last . Now I'd like to propose a toast to the further development of our cooperation .  
 Person2:I'm very delighted too . I'm sure that we'll have a wider range of cooperation . So , let's drink to the signing of our contract .  
 Person1:        Bottoms up !  
 Person2:Cheers . 

informal