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:       Hello , this is 5735647 5 .  
 Person2:Hello , this is John . I wanna speak to Linda , please .  
 Person1:        This is Linda .  
 Person2:Hi , Linda . I want to invite you to a dinner tomorrow evening .  
 Person1:        Really ? What time and which restaurant ?  
 Person2:At seven thirty pm , Longing Chinese restaurant.And I'll go to your home and pick you up at 7 .  
 Person1:        Ok , I'll wait for you at 7pm at home . Anything else ?  
 Person2:No , have a nice day !  
 Person1:        Thank you . Bye .  
 Person2:See you . 

informal