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:       Like to come over to our fancy dress party ?  
 Person2:Oh shame ! I have a class tomorrow .  
 Person1:        Well , then join us some other time .  
 Person2:Yeah . Thanks . And have fun ! 

informal