Given the task definition and input, reply with output. 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'.

Person1: I found out when Jim's birthday is . It's this Friday .
Person2:Let's plan a surprise party for him !
Person1: Can you spread the word and ask everyone to bring some kind of snack food ?
Person2:That's easy . Anything else ?
Person1: Will you call his wife and let her know so that if she is available , she can come too ?
Person2:Won't he be surprised !
Person1: I don't know how old he is though .
Person2:That's O . K . Maybe his wife will spill the beans !
informal