/// design and implement class A with an int private member int num
/// provide accessors and mutators for num
/// default constructor(num = 0) & constructor accepting an int.
/// set num to that int
/// Overload << and >> to diesplay and read numbers.
/// method increment (int a) that adds a to num.
/// design a class B that inherits from A with another private
/// member double d
/// accessors, mutators for d.
/// dedault constructor set d to 0
/// constructor with the double set d to that double, num to 0
/// "" "" one int and one double set num to the int d to the double
/// method increment (int a ) that adds 2 * a to num
/// overload << to display num and d also >> to read num and d