class rat {
public:
    // constructors
    rat	():t(0),b(1) {} rat (int tt):t(tt),b(1) {}
    rat	(int tt,int bb):t(tt),b(bb) {NRM(); }
    rat	(const rat&r):t(r.t),b(r.b) {}
    // accesser functions
    int		n	() const { return t;}
    int d() const {return b;}

       // assignments
       void operator=(const rat&r) {t = r.t; b = r.b;}
       void operator+=(const rat&);
  // other operations
  operator double () const { return t / (double) b;}
  const rat&operator++() {t += b; return *this; }
  const rat operator++(int);
private:
    int t;  // data areas
    int		b;
    void	NRM		(); // operation used internally
    static int	GCD		(int,int);
};

const rat operator+ (const rat&,const rat&);
const rat operator -(const rat&,const rat&);
const rat operator*(const rat&,const rat&);
const rat	operator/(const rat&,const rat&);
const rat operator		 - (const rat&);
bool operator < (						const rat&,const rat&);
bool operator == (const rat&,const rat&);

ostream&operator << (ostream&,const rat&);	istream&operator >> (istream&,rat&);