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:       Have you been served , sir ?  
 Person2:I am just looking , thank you ... Excuse me . Can you tell me where I can buy a pair of shoes ?  
 Person1:        It's on the fourth floor .  
 Person2:Thank you . 

informal