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 want to buy a gift for my father . Will you go with me to choose one for him ?  
 Person2:Sure . Is it your father's birthday ?  
 Person1:        Don't you know ? Tomorrow is Father's Day .  
 Person2:Oh ! How could I forget such an important holiday ?  
 Person1:        You also need to choose a gift for your father , right ?  
 Person2:Yes , let's go . 

informal