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:       Can you work over tonight ?  
 Person2:Sorry , I'm supposed to be with my son .  
 Person1:        Okay , I'll ask Bob to cover it .  
 Person2:Thanks . I appreciate it . 

informal