class SoccerPlayer(object):
    def __init__(self,name,position,back_number):
        self.name=name
        self.position=position
        self.back_number=back_number
    
    def change_back_number(self,new_number):
        print("선수의 등번호를 변경합니다. : From %d to %d"%(self.back_number,new_number))
        self.back_number=new_number

    def __str__(self):
        return "Hello, My name is %s. I play in %s in center"%(self.name,self.position)

jinhyun=SoccerPlayer("jingyun","MF",10)
print(jinhyun)
print("현재 선수의 등번호는 :",jinhyun.back_number)

jinhyun.change_back_number(5)
print("현재 선수의 등번호는 :",jinhyun.back_number)

