Scanf.scanf "%d %d %d %d %d" (fun a b c d e ->
    let calc v =
        let rec loop x i acc =
            if i > v then acc else
                let cur = if i mod 10 > 0 then x else
                          if e <= x then x - e else
                              x 
                in
                loop cur (i + 1) (acc + cur)
        in
        if v = 0 then 0 else loop d 2 d
    in
    Printf.printf "%d\n" @@ calc (a * (b - c))
)