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 C (GCC 9.2.1) (judge verdict: Accepted)

#include <stdio.h>
#define max(a, b) ((a)<(b) ? (b) : (a))

int q;
int a[51], b[51], c[51], d[51];
int ans = 0;

void dfs(int array[], int m, int n){
  if(array[0] == n){
    int sum = 0;
    for(int i=0; i<q; i++){
      if(array[b[i]]-array[a[i]] == c[i]){
	sum = sum + d[i];
      }
    }
    ans = max(ans, sum);    
    return;
  }
  int start = (array[0]==0 ? 1 : array[array[0]]);
  for(int i=start; i<=m; i++){
    array[++array[0]] = i;
    dfs(array, m, n);
    array[0]--;
  }
}

int main(){
  int array[12] = {0};
  int n, m;  scanf("%d%d%d", &n, &m, &q);
  for(int i=0; i<q; i++){
    scanf("%d%d%d%d", &a[i], &b[i], &c[i], &d[i]);
  }
  dfs(array, m, n);
  printf("%d\n", ans);
  return 0;
}