struct Bit {
  bool b;
  Bit(bool b=false):b(b) {}
  Bit(const Bit& bit):b(bit.b) {}

//   operator bool() const {return b;}

  Bit& operator=(bool b)
  {
     this->b = b;
     return *this;
        }


        Bit& operator =(const Bit& bit)
        {
     this->b = bit.b;
     return *this;
        }


  friend const Bit operator ~(const Bit& bit)
  {
    Bit r;
    r.b = ~bit.b;
    return r;
  }

  friend void b_not( Bit& r, const Bit& a )
  { r = (~a); }
};


int main()
{
  Bit b1, b2;
  b_not(b1, b2);
  assert(b1.b != b2.b);
}
