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:       Excuse me . Can I deposit valuables here ?  
 Person2:Yes , you can . Please put your articles in this envelope and seal it .  
 Person1:        OK .  
 Person2:How long would you like us to keep it ?  
 Person1:        Till next Monday when we check out .  
 Person2:All right , ma'am . 

formal