interface Examinable
        {
            public String exam();
        }
        class Course 
        {
            public String exam(String cour)
            {
                return cour + "εĿ";
            }
        }
        class Computer extends Course implements Examinable 
        {
            public String exam(){
                return "ϻ";
            }
        }
        class English extends Course implements Examinable 
        {
            public String exam(){
                return "׼";
            }
        }
        public class Student
        {
            void review(Examinable aCourse) {
                System.out.println(aCourse.exam());
            }
            void review(Course cour , String str ) {
                System.out.println(cour.exam(str));
            }
           public static void main(String[ ] args )         
           { 
              Student stu = new Student();
              stu.review(new Computer());
              stu.review(new English());
              stu.review(new Course() , "Chinese");
           }
}
