static void Main(string[] args)
{
MainStack arrayStack = new BasedOnArraysStack();
MainStack stack = new Stack();
Calculator calculator = new Calculator(arrayStack);
arrayStack.Push(1);
arrayStack.Push(2);
arrayStack.Push(3);
int result = calculator.Difference();
System.Console.WriteLine("{0} ", result);
stack.Push(4);
stack.Push(5);
stack.Push(6);
}