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: Acknowledgments play a necessary part in the interview .
Person2:Sure . Kind acknowledgments can show one's good attainment .
Person1: We often ignore the acknowledgments in our daily life , and consider them as disposable .
Person2:Actually , that's not true . Acknowledgments can help you leave a good impression on others , especially in the public places .
Person1: We should particularly pay attention to acknowledgments in the interview .
Person2:In the beginning of the interview , it is best that you make acknowledgments for the opportunity of the interview .
Person1: Don't forget to say " Thank you " when you take a seat .
Person2:Make acknowledgments as well when the interviewer thinks highly of your dressing , experience , or words .
Person1: You can win a good impression of the interviewer in this way .
Person2:Acknowledgments can also help the job-hunters to show their good attainment .
Person1: Finally , at the end of the interview , make acknowledgments to the interviewer again .
Person2:Smiles and kind attitudes are the basics of acknowledgments .
Output:
informal