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:       It's almost 6:00 . I'd better be going .  
 Person2:Can you stay for dinner ? We'd love to have you join us .  
 Person1:        It's really nice of you . Thanks ! 

informal