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:       Hey Michelle , jump in quick . It's pouring out there !  
 Person2:Oh , hi Melissa . Are you going to the conference too ? I was planning to pick up Mr . Campbell .  
 Person1:        Yes , he told me . We need to pick him up at his hotel and then go to the conference .  
 Person2:Oh I see , okay . So I heard you got married . Congratulations !  
 Person1:        Ah thank you ! I'm very excited . We were going to get married next year , but then we decided to get married on holiday instead . It was wonderful .  
 Person2:That sounds so romantic ! Jack and I were hoping to get married in Europe next year , but we had to postpone our plans . We just don't have the money !  
 Person1:        I know what you mean . I think Shanghai is getting more and more expensive , don't you ?  
 Person2:I sure do . In my opinion , it's actually becoming more expensive than back home .  
 Person1:        Definitely . Oh , there's Mr . Campbell . Driver , can you stop here please ? 

informal