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<bits/stdc++.h>
using namespace std;
#define ll long long int
#define fastio ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0)
#define mp make_pair
#define pb push_back
#define all(v) v.begin(), v.end()
#define ub upper_bound
#define lb lower_bound
#define F first
#define S second

struct abcd{
    int a,b,c,d;
};

ll ans = 0;
vector<abcd> v(55);
int n,m,q;

void checkAll(int arr[], int m, int n, int index, int ma){
    if(n==0){
        ll lans = 0;
        for(int i=0; i<q; i++){
            if(arr[v[i].b-1] - arr[v[i].a-1] == v[i].c) lans += v[i].d;
        }
        ans = max(lans, ans);
    }
    if(n>0){
        for(int i=ma; i<=m; i++){
            arr[index] = i;
            checkAll(arr, m, n-1, index+1, i);
        }
    }
}

int main(){
    fastio;
    cin >> n >> m >> q;

    for(int i=0; i<q; i++){
        cin >> v[i].a >> v[i].b >> v[i].c >> v[i].d;
    }
 
    int arr[10];

    checkAll(arr, m, n, 0, 1);
    cout << ans << endl;
    return 0;
}