1  struct R
       2  {
       3    long long r1, r2;
       4    void copy (R const &r) { r1 = r.r1; r2 = r.r2; }
       5    R ();
       6    explicit R (int, int);
       7    R (R const &r) { copy (r); }
       8    static int compare (R const &, R const &);
       9  };