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 Rust (1.42.0) (judge verdict: Accepted)

// use itertools::Itertools;
use proconio::marker::Usize1;

fn main() {
    proconio::input! {
        n: usize,
        m: usize,
        q: usize,
        xs: [(Usize1,Usize1,usize,i32);q],
    }
    // global
    let mut ans = 0;
    let mut buf = vec![0;n];
    // FnMut closure to update the answer
    let mut update = |arr:&Vec<usize>| {
        let score = xs.iter()
            .map(|(a,b,c,d)|{ if arr[*b] - arr[*a] == *c { *d } else { 0 } })
            .sum::<i32>();
        ans = ans.max(score);
    };
    // dfs
    dfs(&mut buf, 0, m, &mut update);
    println!("{}", ans);
}

fn dfs<F>(buf:&mut Vec<usize>, depth:usize, m:usize, f: &mut F) where F: FnMut(&Vec<usize>) {
    if depth == buf.len() { // leaf
        f(buf);
    } else { // node
        for i in (if depth == 0 { 0 } else { buf[depth-1] })..m {
            buf[depth] = i;
            dfs(buf, depth+1, m, f);       
        }
    }
}