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:       Ma , I really don't know how to thank you .  
 Person2:I'm glad I was able to help .  
 Person1:        It's most kind of you .  
 Person2:Don't mention it . It was the least I could do .  
 Person1:        If there's ever anything I can do for you , Don't hesitate to let me know .  
 Person2:Thank you .  
 Person1:        I'm most grateful .  
 Person2:It was a pleasure . 

informal