class frac {
 //private:
 public:
  unsigned int upper;
  unsigned int lower;
  int sign;  // plus->0, minus->1
  void simplize(frac *);
  unsigned int gcd(unsigned int a, unsigned int b);
 public:
  frac() {}
  frac(int u, unsigned int l);
  frac(int i);
  void set(int u, unsigned int l);
  frac operator + (frac src);
  frac operator - (frac src);
  frac operator * (frac src);
  frac operator / (frac src);
};