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 , I'm sorry for calling this late . May I speak to Peter ?  
 Person2:I'm sorry . He's not in right now .  
 Person1:        When is he coming back ?  
 Person2:He should be back in ten minutes . Could 1 you call back later ?  
 Person1:        I'll call again in thirty minutes . 

formal