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:       I have just had my new paper published .  
 Person2:You have done excellent work .  
 Person1:        I'm going to Britain .  
 Person2:Really ? How did you get the chance ?  
 Person1:        I have been accepted by Oxford University on PhD .  
 Person2:My warmest congratulations on your entering the Oxford University .  
 Person1:        I really appreciate your kind words . 

informal