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: Consider Input: Person1: Excuse me , I bought this sweater yesterday . But when I got home and tried it on , I found it ' s too small .
Person2:Do you have the receipt with you ?
Person1: Yes , here you are .
Person2:Thank you . Do you want your money back ?
Person1: No , can I exchange it for a bigger one ?
Person2:I am afraid this is the biggest size we have .
Person1: Oh , that's too bad .
Person2:Maybe you would like to try this one with the willow pattern . The price is the same and it's bigger .

Output: formal

Input: Consider Input: Person1: The Blacks got divorced .
Person2:Really ? Why ?
Person1: Mr . Black has been getting a little on the side .
Person2:Really ? I am surprised . He doesn't look like a guy who'd ever cheat on his wife , does he ?
Person1: No , he doesn't . Anyway , his wife found out that he has been two-timing for a long time .
Person2:Well , I am really surprised . By the way , have you done anything behind my back ?
Person1: No . The only thing I've ever done behind your back is zipping you up .
Person2:I like that joke , but I hope it's true .

Output: informal

Input: Consider Input: Person1: I'm so angry at Bob for buying a new bike .
Person2:What's the big deal ?
Output: informal