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:       How do you do , Prof.Smith . 
 Person2:How do you do , Ms . Yang.You speak very good English . 
 Person1:        Thank you . I begin to like English even when I was a child . 
 Person2:Where did you learn it ? 
 Person1:        At school , in China.This is my first time to be out of my own country . 
 Person2:It's amazing . 

informal