struct A
{
  int i;
  A():i(0) {}
  A(int i):i(i){}
};

struct B
{
  int j;
  B():j(0) {}
  B(int j): j(j) {}
  B(const A& a):j(a.i){}
};

B operator+(const B b1, B b2)
{
  return B( b1.j + b2.j );
}

int main()
{
  A a(10);
  B b = a + a;
  assert(b.j == 20);
}
