Scanf.scanf "%d %d %d %c" (fun n m k op ->
    let b = Array.init m (fun _ -> Scanf.scanf " %d" (fun b -> b)) in
    let a = Array.init n (fun _ -> Scanf.scanf " %d" (fun a -> a)) in

    let ( +@) a b = (a + b) mod k in
    let ( *@) a b = (a * b) mod k in

    let suma = Array.fold_left (+@) 0 a in
    let sumb = Array.fold_left (+@) 0 b in

    Printf.printf "%d\n" @@
        if op = '*' then suma *@ sumb
                    else n *@ sumb +@ m *@ suma
)