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:       Shall we sing with a karaoke ?  
 Person2:Great idea ! I do it every so often .  
 Person1:        For us , karaoke is becoming a popular entertainment .  
 Person2:Yep . If you are a good singer , your audience will feel comfortable , right ?  
 Person1:        I can not agree with you more . And if you are an awful one , that will be funny .  
 Person2:I remembered Tom is always out of tune . We burst into laughter .  
 Person1:        Is that true ? Shall we invite him to join with us ?  
 Person2:So tricky ! 

informal