output_description: Print the maximum possible score of A.
  
  * * *
input_description: 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
attempt: import sys
  
  sys.setrecursionlimit(700000)
  
  
  def s_in():
      return input()
  
  
  def n_in():
      return int(input())
  
  
  def l_in():
      return list(map(int, input().split()))
  
  
  def print_l(l):
      print(" ".join(map(str, l)))
  
  
  class Interval:
      def __init__(self, li):
          self.li = li
          self.n = len(li)
          self.sum_li = [li[0]]
          for i in range(1, self.n):
              self.sum_li.append(self.sum_li[i - 1] + li[i])
  
      def sum(self, a, b=None):
          if b is None:
              return self.sum(0, a)
  
          res = self.sum_li[min(self.n - 1, b - 1)]
          if a > 0:
              res -= self.sum_li[a - 1]
          return res
  
  
  n, m, q = l_in()
  
  abcd = []
  for _ in range(q):
      abcd.append(l_in())
  
  s = []
  
  
  def check(s):
      return sum(d for a, b, c, d in abcd if s[b - 1] - s[a - 1] == c)
  
  
  def search(s, current):
      tmp = 0
      for d in range(current, m + 1):
          s.append(d)
          if len(s) == n:
              tmp = max(tmp, check(s))
          else:
              tmp = max(tmp, search(s, d))
          s.pop()
  
      return tmp
  
  
  print(search(s, 0))
  
problem_description: 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.
samples: [{"input": "3 4 3\n    1 3 3 100\n    1 2 2 10\n    2 3 2 10", "output": "110\n    \n\nWhen A = \\\\{1, 3, 4\\\\}, its score is 110. Under these conditions, no sequence\nhas a score greater than 110, so the answer is 110.\n\n* * *"}, {"input": "4 6 10\n    2 4 1 86568\n    1 4 0 90629\n    2 3 0 90310\n    3 4 1 29211\n    3 4 3 78537\n    3 4 2 8580\n    1 2 1 96263\n    1 4 2 2156\n    1 2 0 94325\n    1 4 3 94328", "output": "357500\n    \n\n* * *"}, {"input": "10 10 1\n    1 10 9 1", "output": "1"}]