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 . May I speak to David ?  
 Person2:Who ?  
 Person1:        David Bush .  
 Person2:There ’ s nobody here by that name .  
 Person1:        Sorry , I dialed the wrong number . 

informal