static void Main(string[] args)
{
Addition a = new Addition();
Substraction s = new Substraction();
Calculator c = new Calculator(a);
Console.WriteLine(c.doaction(10, 15));
Console.ReadKey();
Calculator c1 = new Calculator(s);
Console.WriteLine(c1.doaction(10, 15));
Console.ReadKey();
Calculator2 c2 = new Calculator2();
c2.operation = a;
Console.WriteLine(c2.doaction(20, 4));
Console.ReadKey();
c2.operation = s;
Console.WriteLine(c2.doaction(16, 11));
Console.ReadKey();
}
