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:       What ? How could you forget to reserve the concert tickets ?  
 Person2:I'm sorry . I forget all about it .  
 Person1:        How could you ? I reminded you just this morning .  
 Person2:It's leap my mind . I really feel terrible about it .  
 Person1:        I have been looking forward to this performance all month .  
 Person2:I'm really sorry I let you down . I'll make it up to you somehow . 

informal