#include <bits/stdc++.h>
using namespace std;
void per() { cerr << endl; }
template <typename Head, typename... Tail>
void per(Head H, Tail... T) {
  cerr << H << ' ';
  per(T...);
}
template <class T>
bool uin(T& a, T b) {
  return a > b ? (a = b, true) : false;
}
template <class T>
bool uax(T& a, T b) {
  return a < b ? (a = b, true) : false;
}
template <class U, class V>
ostream& operator<<(ostream& out, const pair<U, V>& a) {
  return out << "(" << a.first << ", " << a.second << ")";
}
template <class U, class V>
istream& operator>>(istream& in, pair<U, V>& a) {
  return in >> a.first >> a.second;
}
template <typename W,
          typename T = typename enable_if<!is_same<W, string>::value,
                                          typename W::value_type>::type>
ostream& operator<<(ostream& out, const W& v) {
  out << "{ ";
  for (const auto& first : v) out << first << ", ";
  return out << '}';
}
template <class T>
void readArr(T from, T to) {
  for (auto i = from; i != to; ++i) cin >> *i;
}
mt19937 mrand(1337);
unsigned int myRand32() { return mrand() & (unsigned int)(-1); }
unsigned long long myRand64() {
  return ((unsigned long long)myRand32() << 32) ^ myRand32();
}
const int mod = 1000000007;
void add(int& a, int b) {
  a += b;
  if (a >= mod) a -= mod;
}
void dec(int& a, int b) {
  a -= b;
  if (a < 0) a += mod;
}
int mult(int a, int b) { return a * (long long)b % mod; }
int bp(int a, int b) {
  int res = 1;
  while (b > 0) {
    if (b & 1) res = mult(res, a);
    a = mult(a, a);
    b >>= 1;
  }
  return res;
}
struct Dinic {
  struct edge {
    int to, flow, cap;
  };
  const static int N = 55 * 55 + 55 * 55;
  vector<edge> e;
  vector<int> g[N + 7];
  int dp[N + 7];
  int ptr[N + 7];
  void clear() {
    for (int i = 0; i < N + 7; i++) g[i].clear();
    e.clear();
  }
  void addEdge(int a, int b, int cap) {
    g[a].push_back(e.size());
    e.push_back({b, 0, cap});
    g[b].push_back(e.size());
    e.push_back({a, 0, 0});
  }
  int minFlow, start, finish;
  bool bfs() {
    for (int i = 0; i < N; i++) dp[i] = -1;
    dp[start] = 0;
    vector<int> st;
    int uk = 0;
    st.push_back(start);
    while (uk < st.size()) {
      int v = st[uk++];
      for (int to : g[v]) {
        auto ed = e[to];
        if (ed.cap - ed.flow >= minFlow && dp[ed.to] == -1) {
          dp[ed.to] = dp[v] + 1;
          st.push_back(ed.to);
        }
      }
    }
    return dp[finish] != -1;
  }
  int dfs(int v, int flow) {
    if (v == finish) return flow;
    for (; ptr[v] < g[v].size(); ptr[v]++) {
      int to = g[v][ptr[v]];
      edge ed = e[to];
      if (ed.cap - ed.flow >= minFlow && dp[ed.to] == dp[v] + 1) {
        int add = dfs(ed.to, min(flow, ed.cap - ed.flow));
        if (add) {
          e[to].flow += add;
          e[to ^ 1].flow -= add;
          return add;
        }
      }
    }
    return 0;
  }
  int dinic(int start, int finish) {
    Dinic::start = start;
    Dinic::finish = finish;
    int flow = 0;
    for (minFlow = (1 << 30); minFlow; minFlow >>= 1) {
      while (bfs()) {
        for (int i = 0; i < N; i++) ptr[i] = 0;
        while (int now = dfs(start, (int)2e9 + 7)) flow += now;
      }
    }
    return flow;
  }
} dinic;
int n, h, m;
int le[55];
int ri[55];
int first[55];
int c[55];
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cin >> n >> h >> m;
  int res = n * h * h;
  int start = n * h + m;
  int finish = start + 1;
  for (int i = 0; i < m; ++i) cin >> le[i] >> ri[i] >> first[i] >> c[i];
  for (int i = 0; i < n; ++i) {
    int now = i * h;
    dinic.addEdge(start, now, h * h);
    for (int j = 0; j + 1 < h; ++j) {
      dinic.addEdge(now, now + 1, h * h - (j + 1) * (j + 1));
      ++now;
    }
    dinic.addEdge(now, finish, 0);
  }
  for (int i = 0; i < m; ++i) {
    int now = n * h + i;
    if (first[i] == h) continue;
    for (int j = le[i] - 1; j < ri[i]; ++j) {
      dinic.addEdge(j * h + first[i], now, 1e9 + 7);
    }
    dinic.addEdge(now, finish, c[i]);
  }
  cout << res - dinic.dinic(start, finish);
}
