static void Main()
{
StaticDemo obj = new StaticDemo();
obj.sub(); // non -static method
obj.Sum(); //instance
Console.WriteLine(obj.a);
Console.WriteLine(b);
div();//static method
Console.WriteLine();
}
static void Main()
{
Console.WriteLine("static Demo 2");
StaticDemo.div();
StaticDemo obj = new StaticDemo();
obj.sub();
obj.Sum();
int c = obj.a;
int a = StaticDemo.b;
Console.ReadLine();
}