struct S {
  v: i32
}

fn main()
{
  let v  = std::cell::RefCell::new(S{v:666});
  let s  = std::rc::Rc::new(v);
  let r1 = s.clone();
  let r2 = s.clone();

  println!("{} {}",
           (*r1.borrow()).v, (*r2.borrow()).v);
  {
    let mut r3 = s.borrow_mut();
    r3.v = 0;
  }
  println!("{} {}",
           (*r1.borrow()).v, (*r2.borrow()).v)
}