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 was just watching a documentary on tv about people use dogs for various purpose . It was very interesting .  
 Person2:I love dogs . They have been used as guards for centuries . Nowadays , they are often used to find illegal drugs and bombs by the police and customs officers .  
 Person1:        The documentary also pointed out that they are used by shepherds to round up sheep and by rescue workers to find people trapped under rubble or snow .  
 Person2:Horses are useful to people too . We use them for sports and recreation .  
 Person1:        Don ’ t forget that horses are still used in many countries to pull ploughs and carts .  
 Person2:Can you ride a horse ?  
 Person1:        Yes , I can . I don ’ t ride regularly though . How about you ?  
 Person2:I can ride too . Perhaps we could go horse riding together at the weekend ?  
 Person1:        What a good idea ! 

informal