What will be the Output? | JavaScript

    var boy = {
            name:"Natasha",
            birthday : {
                date : 1,
                month : 'April',                    
            }   
        }

    var girl = { ...boy } ;  // copying object

    boy.name = 'Nitish' ;  
    boy.birthday.date = 31 ;
    boy.birthday.month = "December" ;

   console.log(boy) ;

   console.log(girl);