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 , sir . Can I help you ?  
 Person2:I'd be glad to have your help . Could you make the air-conditioner cooler ?  
 Person1:        I'm sorry . We can not regulate the air-conditioner . As soon as the plane takes off we'll be able to get better ventilation , and the temperature here will drop . Let me get a wet towel for you at the moment .  
 Person2:Good idea .  
 Person1:        Your wet towel , sir .  
 Person2:Thank you . Could I have something cold to drink ?  
 Person1:        Yes . We have mineral water , orange juice , coke , which do you prefer ?  
 Person2:Orange juice , please .  
 Person1:        Would you like some ice in your drink ?  
 Person2:Yes .  
 Person1:        How much would you like ?  
 Person2:One or two cubes will be OK .  
 Person1:        Here you are , sir .  
 Person2:I'm awfully sorry to have bothered you .  
 Person1:        It's my pleasure .  
 Person2:Please accept this tip . 

informal