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:       All right . But these are black and I don ’ t like black shoes . They ’ re dull .  
 Person2:Well , black is a better color than pink . Pink ’ s for girls .  
 Person1:        Then why are you wearing black shoes ?  
 Person2:Because ... oh , all right . You win . Let ’ s pay for them and go .  
 Person1:        Hey , thanks , mum . 

informal