static void Main(string[] args)
{
Student Marshall = new Student();
Marshall.Name = "Marshall";
InternationalStudent Xiong = new InternationalStudent();
Xiong.Name = "Xiong";
Console.WriteLine(Marshall.Name);
Console.WriteLine(Xiong.Name);
double tuition = Marshall.GetTuition(3);
Console.WriteLine(tuition);
tuition = Xiong.GetInternationalTuition(3);
Console.WriteLine(tuition);
}