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:       Hi , I ’ m Susan.What ’ s your name , please ? 
 Person2:My name is Zhang Ming.Nice to meet you , Susan . 
 Person1:        Where do you come from ? 
 Person2:I come from China.Are you American ? 
 Person1:        Yeah , that ’ s right.SO what are you studying ? 
 Person2:Business management 
 Person1:        That sounds interesting . 

formal