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:       You look so happy , Anna . Any good news ? 
 Person2:Yes . I ’ Ve won the first prize in the math contest . 
 Person1:        Really ? Congratulations ! 
 Person2:Thank you , Paul . 
 Person1:        By the way , would you like to have dinner with me tomorrow evening ? Tomorrow is my birthday . 
 Person2:Good , happy birthday to you ! 
 Person1:        Not so soon . It ’ s not my birthday today . Well , you ’ ll come , won ’ t you ? 
 Person2:Sure , I will . Thank you for inviting me . 
 Person1:        My pleasure . 

informal