module M = Map.Make (struct type t = int let compare = compare end)

let () =
    let split s =
        let rec loop i cur flag acc =
            if i = String.length s then ( if flag then cur :: acc else acc) else (
                match flag, s.[i] with
                | true,  ' ' -> loop (i + 1) "" false (cur :: acc)
                | false, ' ' -> loop (i + 1) "" false acc
                | true,  v   -> loop (i + 1) (Printf.sprintf "%s%c" cur v) true acc
                | false, v   -> loop (i + 1) (Printf.sprintf "%s%c" cur v) true acc
            )
        in
        List.map int_of_string (List.rev (loop 0 "" false []))
    in
    let main () =
        let n, k = Scanf.sscanf (read_line ()) "%d %d" (fun n k -> n, k) in
        let a = Array.of_list (split (read_line ())) in
        let arr = Array.make (n + 1) 0 in
        let rec loop i sum =
            if i < n then (
                let sum = sum + a.(i) - 1 in
                arr.(i + 1) <- sum mod k;
                loop (i + 1) sum
            )
        in
        loop 0 0;
        let add k v map = M.add k (v + try M.find k map with _ -> 0) map in
        let rec loop i map acc =
            if i > n then acc else
                let map = if i >= k then add arr.(i - k) (-1) map else map in
                let acc = acc + try M.find arr.(i) map with _ -> 0 in
                let map = add arr.(i) 1 map in
                loop (i + 1) map acc
        in
        let r = loop 1 (M.add 0 1 M.empty) 0 in
        Printf.printf "%d\n" r
    in
    main ()