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)

macro_rules! input {
    (source = $s:expr, $($r:tt)*) => {
        let mut iter = $s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
    ($($r:tt)*) => {
        let mut s = {
            use std::io::Read;
            let mut s = String::new();
            std::io::stdin().read_to_string(&mut s).unwrap();
            s
        };
        let mut iter = s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
}

macro_rules! input_inner {
    ($iter:expr) => {};
    ($iter:expr, ) => {};

    ($iter:expr, $var:ident : $t:tt $($r:tt)*) => {
        let $var = read_value!($iter, $t);
        input_inner!{$iter $($r)*}
    };
}

macro_rules! read_value {
    ($iter:expr, ( $($t:tt),* )) => {
        ( $(read_value!($iter, $t)),* )
    };

    ($iter:expr, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| read_value!($iter, $t)).collect::<Vec<_>>()
    };

    ($iter:expr, chars) => {
        read_value!($iter, String).chars().collect::<Vec<char>>()
    };

    ($iter:expr, usize1) => {
        read_value!($iter, usize) - 1
    };

    ($iter:expr, $t:ty) => {
        $iter.next().unwrap().parse::<$t>().expect("Parse error")
    };
}

// fn main() {
//     input! {
//         n: usize,
//         m: i32,
//         q: usize,
//         abcd: [(usize,usize,i32,i32);q],
//     }
//     let mut val = vec![1i32; n + 1];

//     println!("{:?}", dfs(&mut val, 1, m, &abcd));
// }

// fn dfs(buf: &mut Vec<i32>, d: usize, ub: i32, abcd: &Vec<(usize, usize, i32, i32)>) -> i32 {
//     let mut sum = 0;
//     if d == buf.len() {
//         for &(a, b, c, d) in abcd {
//             if buf[b] - buf[a] == c {
//                 sum += d;
//             }
//         }
//     } else {
//         for i in buf[d - 1]..ub + 1 {
//             buf[d] = i as i32;
//             sum = std::cmp::max(sum, dfs(buf, d + 1, ub, abcd));
//         }
//     }
//     sum
// }

fn main() {
    input! {
       n: usize,
       m: i32,
       q: usize,
       abcd: [(usize,usize,i32,i32);q],
    }

    // 今回の問題は前の数以上の数を入れていくので
    // 最初の基準となる数が必要。
    // [1 ,...n個]
    //  ↑これを基準点にする
    let mut buf = vec![1i32; n + 1];
    println!("{}", dfs(&mut buf, 1, m, &abcd))
}

fn dfs(buf: &mut Vec<i32>, index: usize, ud: i32, abcd: &Vec<(usize, usize, i32, i32)>) -> i32 {
    let mut result = 0;
    if index == buf.len() {
        // 最大値を計算
        for &(a, b, c, d) in abcd {
            if buf[b] - buf[a] == c {
                result += d;
            }
        }
    } else {
        for j in buf[index - 1]..ud + 1 {
            buf[index] = j;
            result = std::cmp::max(result, dfs(buf, index + 1, ud, abcd));
        }
    }
    result
}