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:       Have the aerobic classes any effect on you ?  
 Person2:Sure , great effect.My weight has dropped from 150 pounds to 120 .  
 Person1:        Congratulations ! That's really something beyond my imagination . 

informal