static void Main(string[] args)
{
IChain chain1 = new Add();
IChain chain2 = new Substract();
IChain chain3 = new Multi();
IChain chain4 = new Devide();
chain1.setNextChain(chain2);
chain2.setNextChain(chain3);
chain3.setNextChain(chain4);
Num request = new Num(2, 4, "add");
chain1.calculate(request);
}