// the Bus class
class Bus
{
   private:
	  int capacity;      // passenger capacity
	  int currNum;       // passengers in the bus
   public:
      // constructor
      Bus();

      // adjust passenger number
      void addPass(int newPass); // adds newPass new passengers
      void subPass(int leaving); // leaving passengers leave

	  // test if no passengers
	  bool empty();
};

// ***********************************************************
//      Bus class implementation
// ***********************************************************

      // constructor
      Bus::Bus()
	  {
		  currNum = 0; capacity = 100;
	  }

      // adjust passenger numbers
      void Bus::addPass(int newPass)
	  { 
		  currNum = currNum + newPass;
	  }

      void Bus::subPass(int leaving)
	  {
		  currNum = currNum - leaving;
	  }

      // test for empty bus
	  bool Bus::empty()
	  {
          bool isEmpty = false;
		  if (currNum <= 0)
		  {
               isEmpty = true;
		  }
		  return isEmpty;
	  }