Scanf.scanf "%d" (fun n ->
    let rec loop t g acc =
        if t * 5 > n then acc else
        if g > t || t * 5 + g * 2 > n then loop (t + 1) 0 acc else
            let acc = if (n - t * 5 - g * 2) mod 3 = 0 then acc + 1 else acc in
            loop t (g + 1) acc
    in
    loop 0 0 0 |> Printf.printf "%d\n"
)