/**
 *    author:  math2do
 *    created: 02.05.2020 23:15:39 IST
**/

#include <bits/stdc++.h>

using namespace std;

template <typename A, typename B>
string to_string(pair<A, B> p);
 
template <typename A, typename B, typename C>
string to_string(tuple<A, B, C> p);
 
template <typename A, typename B, typename C, typename D>
string to_string(tuple<A, B, C, D> p);
 
string to_string(const string& s) {
  return '"' + s + '"';
}
 
string to_string(const char* s) {
  return to_string((string) s);
}
 
string to_string(bool b) {
  return (b ? "true" : "false");
}

string to_string(const char &ch) {
  return "'" + string(1, ch) + "'";
}

string to_string(vector<bool> v) {
  bool first = true;
  string res = "{";
  for (int i = 0; i < static_cast<int>(v.size()); i++) {
    if (!first) {
      res += ", ";
    }
    first = false;
    res += to_string(v[i]);
  }
  res += "}";
  return res;
}
 
template <size_t N>
string to_string(bitset<N> v) {
  string res = "";
  for (size_t i = 0; i < N; i++) {
    res += static_cast<char>('0' + v[i]);
  }
  reverse(res.begin(), res.end());
  return res;
}

template <typename A>
string to_string(A v) {
  bool first = true;
  string res = "{";
  for (const auto &x : v) {
    if (!first) {
      res += ", ";
    }
    first = false;
    res += to_string(x);
  }
  res += "}";
  return res;
}
 
template <typename A, typename B>
string to_string(pair<A, B> p) {
  return "(" + to_string(p.first) + ", " + to_string(p.second) + ")";
}
 
template <typename A, typename B, typename C>
string to_string(tuple<A, B, C> p) {
  return "(" + to_string(get<0>(p)) + ", " + to_string(get<1>(p)) + ", " + to_string(get<2>(p)) + ")";
}
 
template <typename A, typename B, typename C, typename D>
string to_string(tuple<A, B, C, D> p) {
  return "(" + to_string(get<0>(p)) + ", " + to_string(get<1>(p)) + ", " + to_string(get<2>(p)) + ", " + to_string(get<3>(p)) + ")";
}

void debug_out() { cerr << endl; }
 
template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
  cerr << " " << to_string(H);
  debug_out(T...);
}
 
#ifdef LOCAL
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#else
#define debug(...) 42
#endif

int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  int n, m, q;
  cin >> n >> m >> q;
  vector <tuple <int, int, int, int> > quad(q);
  for (int i = 0; i < q; i++) {
    cin >> get<0>(quad[i]); get<0>(quad[i])--;
    cin >> get<1>(quad[i]); get<1>(quad[i])--;
    cin >> get<2>(quad[i]); 
    cin >> get<3>(quad[i]); 
  }
  int ans = numeric_limits<int>::min();
  vector <int> arr;
  function <void(int, int)> recur = [&] (int last, int i) {
    if (i == n) {       
      int sum = 0;
      for (int j = 0; j < q; j++) {
        if (arr[get<1>(quad[j])] - arr[get<0>(quad[j])] == get<2>(quad[j])) {
          sum += get<3>(quad[j]);
        } 
      }
      ans = max(ans, sum);
      return; 
    } 
    for (int num = last; num <= m; num++) {
      arr.push_back(num);
      recur(num, i + 1);
      arr.pop_back();
    } 
  };
  for (int num = 1; num <= m; num++) {
    arr.push_back(num);
    recur(num, 1);
    arr.pop_back();
  } 
  cout << ans << endl;
  return 0;
}


Measured memory_bytes: 3552