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)

#![allow(
    non_snake_case,
    unused_variables,
    unused_assignments,
    unused_mut,
    dead_code
)]
use proconio::input;
use proconio::marker::Usize1;
//use proconio::marker::Chars;
//use std::collections::HashSet;
use std::cmp::*;
fn main() {
    input! {
        n:usize,
        m:i32,
        q:i32,
        abcd:[(Usize1,Usize1,i32,i32);q]
    }
    let mut ans = 0;
    let mut A: Vec<i32> = vec![1; n];
    A[n - 1] = 0;

    let mut ans = 0;
    while next(&mut A, n, m) {
        let mut tmp = 0;
        for &(a, b, c, d) in abcd.iter() {
            if A[b] - A[a] == c {
                tmp += d;
            }
        }
        //println!("a={:?}, tmp={}", A, tmp);
        ans = max(ans, tmp);
    }
    println!("{}", ans);
}

fn next(a: &mut Vec<i32>, n: usize, m: i32) -> bool {
    let mut i = n - 1;
    while a[i] == m {
        if i == 0 {
            return false;
        } else {
            i -= 1;
        }
    }
    a[i] += 1;
    for j in i + 1..n {
        a[j] = a[i];
    }
    true
}