trait MyOperations {
  fn my_div(self, den: i64) -> Option<i64>;
}

impl MyOperations for i64 {
  fn my_div(self, den: i64) -> Option<i64>
  {
    if den != 0 {
      Some(self / den)
    } else {
      None
    }
  }
}

fn my_sum(a: &Option<i64>, b:&Option<i64>) -> Option<i64>
{
  let va = (*a)?;
  let vb = (*b)?;

  Some(va + vb)
}

fn my_print(v: &Option<i64>)
{
  match v {
    Some(i) => print!("{}", i),
    None => print!("None"),
  }
}

fn main()
{
  let a = 6.my_div(3);
  let b = 8.my_div(2);
  let c = 6.my_div(0);
  let r1 = my_sum(&a, &b);
  let r2 = my_sum(&a, &c);

  print!("6 / 3 + 8 / 2 = ");
  my_print(&r1);
  println!("");
  print!("6 / 3 + 6 / 0 = ");
  my_print(&r2);
  println!("");
}