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:       Mum , this is for you .  
 Person2:Oh , flowers ! What for , my dear ?  
 Person1:        Happy Mother's Day to you , Mum !  
 Person2:Oh , thank you.You are so sweet ! 

informal