You will be given a definition of a task first, then some input of the task.
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: Who ' s this ? your girl-friend ?
Person2:No , it ' s my sister .
Person1: How old is she ?
Person2:She ' s 18 .
Person1: She is tall ?
Person2:Yes , she is .
Person1: And she is thin , isn ' t she ?
Person2:Well , just a little thin .
Output:
formal