//-------------------------------------
void fn(Student& x){
switch(x.type){
case Student::STUDENT:
x.calcTuition(); break;
case Student::GRADUATESTUDENT:{
GraduateStudent& gx = static_cast<GraduateStudent&>(x);
gx.calcTuition(); break;}
case Student::DOCTOR:{
Doctor& dx = static_cast<Doctor&>(x);
dx.calcTuition(); break;}
}
}//------------------------------------
