Scanf.scanf "%s %s" (fun s t ->
    let lens = String.length s in
    let lent = String.length t in

    let rec loop i acc =
        if i + lent > lens then acc else
            if String.sub s i lent <> t then loop (i + 1) acc else
                if lent = 1 then -1 else
                    loop (i + lent - 1) (acc + 1)
    in
    loop 0 0 |> Printf.printf "%d\n"
)