#![allow(non_snake_case)]
#![allow(dead_code)]
#![allow(unused_macros)]
#![allow(unused_imports)]

use std::str::FromStr;
use std::io::*;
use std::collections::*;
use std::cmp::*;

struct Scanner<I: Iterator<Item = char>> {
    iter: std::iter::Peekable<I>,
}

macro_rules! exit {
    () => {{
        exit!(0)
    }};
    ($code:expr) => {{
        if cfg!(local) {
            writeln!(std::io::stderr(), "===== Terminated =====")
                .expect("failed printing to stderr");
        }
        std::process::exit($code);
    }}
}

impl<I: Iterator<Item = char>> Scanner<I> {
    pub fn new(iter: I) -> Scanner<I> {
        Scanner {
            iter: iter.peekable(),
        }
    }

    pub fn safe_get_token(&mut self) -> Option<String> {
        let token = self.iter
            .by_ref()
            .skip_while(|c| c.is_whitespace())
            .take_while(|c| !c.is_whitespace())
            .collect::<String>();
        if token.is_empty() {
            None
        } else {
            Some(token)
        }
    }

    pub fn token(&mut self) -> String {
        self.safe_get_token().unwrap_or_else(|| exit!())
    }

    pub fn get<T: FromStr>(&mut self) -> T {
        self.token().parse::<T>().unwrap_or_else(|_| exit!())
    }

    pub fn vec<T: FromStr>(&mut self, len: usize) -> Vec<T> {
        (0..len).map(|_| self.get()).collect()
    }

    pub fn mat<T: FromStr>(&mut self, row: usize, col: usize) -> Vec<Vec<T>> {
        (0..row).map(|_| self.vec(col)).collect()
    }

    pub fn char(&mut self) -> char {
        self.iter.next().unwrap_or_else(|| exit!())
    }

    pub fn chars(&mut self) -> Vec<char> {
        self.get::<String>().chars().collect()
    }

    pub fn mat_chars(&mut self, row: usize) -> Vec<Vec<char>> {
        (0..row).map(|_| self.chars()).collect()
    }

    pub fn line(&mut self) -> String {
        if self.peek().is_some() {
            self.iter
                .by_ref()
                .take_while(|&c| !(c == '\n' || c == '\r'))
                .collect::<String>()
        } else {
            exit!();
        }
    }

    pub fn peek(&mut self) -> Option<&char> {
        self.iter.peek()
    }
}

struct Solver {
    N: usize,
    M: usize,
    Q: usize,
    abcd: Vec<(usize, usize, usize, usize)>,
    A: Vec<usize>,
    ans: usize,
}

impl Solver {
    fn new(N: usize, Q: usize, M: usize, abcd: Vec<(usize, usize, usize, usize)>) -> Solver {
        Solver {
            N: N,
            M: M,
            Q: Q,
            abcd: abcd,
            A: vec![0; N],
            ans: 0,
        }
    }
    fn dfs(&mut self, i: usize, prev: usize) {
        if i == self.N {
            self.solve();
            return;
        }
        for n in prev..=self.M {
            self.A[i] = n;
            self.dfs(i+1, n);
        }
    }
    fn solve(&mut self) {
        let mut res = 0;
        for i in 0..self.Q {
            let (a, b, c, d) = self.abcd[i];
            if self.A[b] - self.A[a] == c {
                res += d;
            }
        }
        self.ans = max(self.ans, res);
    }
}

fn main() {
    let cin = stdin();
    let cin = cin.lock();
    let mut sc = Scanner::new(cin.bytes().map(|c| c.unwrap() as char));
    let N: usize = sc.get();
    let M: usize = sc.get();
    let Q: usize = sc.get();
    let mut abcd = Vec::new();
    for _ in 0..Q {
        let a: usize = sc.get::<usize>()-1;
        let b: usize = sc.get::<usize>()-1;
        let c: usize = sc.get::<usize>();
        let d: usize = sc.get::<usize>();
        abcd.push((a, b, c, d));
    }
    let mut s = Solver::new(N, Q, M, abcd);
    s.dfs(0, 1);
    println!("{}", s.ans);
}


Measured memory_bytes: 2092