struct S {
  v: i32
}

fn main() {
  let mut p = Box::new(S {v: 5});

  println!("P.v={}", p.v);
  p.v = 666;
  {
    let p2 = &p;
    let p1 = &p;

    println!("P1.v={}", p1.v);
    //p1.v = 0;
    println!("P1.v={}", p2.v);
  }
  println!("P.v={}", p.v)
}