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:       When will the ceremony begin ?  
 Person2:The ceremony will begin at 9 0 ' clock . After the ceremony , there's a reception . By the way , do you know why they have chosen September 9th for their wedding ceremony ?  
 Person1:        No idea .  
 Person2:As in English , Chinese also has some lucky numbers . The number 9 stands for perpetuity in Chinese . 

formal