Problem:
Score : 300 points

Problem Statement

Given are positive integers N, M, Q, and Q quadruples of integers ( a_i , b_i , c_i , d_i ).

Consider a sequence A satisfying the following conditions:

A is a sequence of N positive integers.

1 \leq A_1 \leq A_2 \le \cdots \leq A_N \leq M.

Let us define a score of this sequence as follows:

The score is the sum of d_i over all indices i such that A_{b_i} - A_{a_i} = c_i. (If there is no such i, the score is 0.)

Find the maximum possible score of A.

Constraints

All values in input are integers.

2 ≤ N ≤ 10

1 \leq M \leq 10

1 \leq Q \leq 50

1 \leq a_i < b_i \leq N ( i = 1, 2, ..., Q )

0 \leq c_i \leq M - 1 ( i = 1, 2, ..., Q )

(a_i, b_i, c_i) \neq (a_j, b_j, c_j) (where i \neq j)

1 \leq d_i \leq 10^5 ( i = 1, 2, ..., Q )

Input

Input is given from Standard Input in the following format:

N M Q
a_1 b_1 c_1 d_1
:
a_Q b_Q c_Q d_Q

Output

Print the maximum possible score of A.

Sample Input 1

3 4 3
1 3 3 100
1 2 2 10
2 3 2 10

Sample Output 1

110

When A = \{1, 3, 4\}, its score is 110. Under these conditions, no sequence has a score greater than 110, so the answer is 110.

Sample Input 2

4 6 10
2 4 1 86568
1 4 0 90629
2 3 0 90310
3 4 1 29211
3 4 3 78537
3 4 2 8580
1 2 1 96263
1 4 2 2156
1 2 0 94325
1 4 3 94328

Sample Output 2

357500

Sample Input 3

10 10 1
1 10 9 1

Sample Output 3

1

Solution in OCaml (4.10.0) (judge verdict: Accepted)

open Batteries
module EnumL = Enum.Labels
module ListL = List.Labels
module ArrayL = Array.Labels

let dbg0 x = Printf.eprintf "[debug]%s\n" @@ dump x
let dbg1 x = dbg0 x; x

let id = identity

let (++) n m = List.range n `To m
let (++^) n m = if n < m then List.range n `To (pred m) else []

let scan fmt = Scanf.sscanf (read_line ()) fmt

let scan_lines n fmt f =
  if n = 0 then []
  else List.map (fun _ -> scan fmt f) (1 ++ n)

let scan_list sep cnv =
  let line = read_line () in
  (match sep with
   | None -> List.map String.of_char @@ String.to_list line
   | Some sep -> String.split_on_char sep line)
  |> List.map cnv

let scan_array ?sep cnv = Array.of_list @@ scan_list sep cnv

let scan_matrix n m e ?sep conv =
  let arr = Array.make_matrix n m e in
  ListL.iter (0 ++^ n)
    ~f:(fun i -> arr.(i) <- Array.of_list @@ scan_list sep conv);
  arr

let rec powerset e =
  match Enum.get e with
  | None -> Enum.singleton @@ Enum.empty ()
  | Some v ->
    let f = powerset e in
    let g = Enum.clone f in
    EnumL.map f ~f:(fun x -> let y = Enum.clone x in push y v; y)
    |>  Enum.append g

let permutations l =
  let rec aux l =
    let rec interleave x = function
      | [] -> [[x]]
      | (hd::tl) as lst ->
        (x::lst) ::
        (ListL.map ~f:(List.cons hd)  @@ interleave x tl)
    in
    match l with
    | [] -> [[]]
    | hd::tl -> List.concat @@ List.map (interleave hd) @@ aux tl in
  let l = List.sort (List.compare Int.compare) @@ aux @@ List.of_enum l in
  List.enum % ListL.map ~f:List.enum @@ l

let intersection l =
  EnumL.filter ~f:(fun x -> EnumL.exists ~f:((=) x) @@ Enum.clone l)

let lower_bound n f =
  let rec aux l u =
    if u - l > 1 then
      let m = (l + u) / 2 in
      if f m then aux l m
      else aux m u
    else u in aux (-1) n

let between n x m = n <= x && x < m

let inc_seq len m =
  let rec aux rest n =
    if rest = 0 then [[]]
    else if n = succ m then []
    else
      (ListL.map ~f:(fun l -> n::l) @@ aux (pred rest) n)
      @ aux rest (succ n)
  in
  aux len 1

let (n,m,q) = scan "%d %d %d"  Tuple3.make
let qs = scan_lines q "%d %d %d %d" Tuple4.make

let () =
  inc_seq n m
  |> ListL.map ~f:Array.of_list
  (* |> (fun l -> List.print ~sep:"\n" (Array.print Int.print) stderr l; l) *)
  |> ListL.map ~f:(fun l ->
      ListL.map ~f:(fun (a,b,c,d) ->
          if l.(pred b) - l.(pred a) = c then d else 0)
        qs |> List.sum)
  |> List.max
  |> Printf.printf "%d\n"