Scanf.scanf "%s %d %d" (fun s t u ->
    let n = String.length s in
    let rec loop i acc =
        if i = n then acc else
            if i = t || i = u then loop (i + 1) acc else
                loop (i + 1) (Printf.sprintf "%s%c" acc s.[i])
    in
    loop 0 "" |> print_endline
)