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:       Why not go to the supermarket today , the coupon will be past due in three days .  
 Person2:Sure . Can we use it in Today Supermarket ?  
 Person1:        Let me check . Yes , we can .  
 Person2:I really don't know what to buy . 

informal