#include <bits/stdc++.h>
inline int min(const int &first, const int &second) {
  return (((second - first) >> (32 - 1)) & (first ^ second)) ^ first;
}
inline int max(const int &first, const int &second) {
  return (((second - first) >> (32 - 1)) & (first ^ second)) ^ second;
}
inline long long min(const long long &first, const long long &second) {
  return (((second - first) >> (64 - 1)) & (first ^ second)) ^ first;
}
inline long long max(const long long &first, const long long &second) {
  return (((second - first) >> (64 - 1)) & (first ^ second)) ^ second;
}
using namespace std;
char string_in_buffer[(int)260];
void fast_scan(int &first) { scanf("%d", &first); }
void fast_scan(long long &first) { scanf("%lld", &first); }
void fast_scan(unsigned long long &first) { scanf("%llu", &first); }
void fast_scan(double &first) { scanf("%lf", &first); }
void fast_scan(long double &first) { scanf("%Lf", &first); }
void fast_scan(char &first) {
  scanf("%c", &first);
  if (first == '\n') {
    fast_scan(first);
  }
}
void fast_scan(string &first) {
  scanf("%s", string_in_buffer);
  first = string(string_in_buffer);
}
template <class TFirst, class TSecond>
void fast_scan(pair<TFirst, TSecond> &p) {
  fast_scan(p.first);
  fast_scan(p.second);
}
template <class T>
void fast_scan(vector<T> &v) {
  for (auto &first : v) fast_scan(first);
}
void fast_print(const int &first) { printf("%d", first); }
void fast_print(const unsigned int &first) { printf("%u", first); }
void fast_print(const long long &first) { printf("%lld", first); }
void fast_print(const unsigned long long &first) { printf("%llu", first); }
void fast_print(const double &first) { printf("%.15lf", first); }
void fast_print(const long double &first) { printf("%.15Lf", first); }
void fast_print(const char &first) { printf("%c", first); };
void fast_print(const string &first) { printf("%s", first.c_str()); }
void fast_print(const char v[]) { fast_print((string)v); }
template <class TFirst, class TSecond>
void fast_print(const pair<TFirst, TSecond> &p) {
  fast_print(p.first);
  fast_print(' ');
  fast_print(p.second);
}
template <class T>
void fast_print(const vector<T> &v) {
  if (v.empty()) return;
  fast_print(v[0]);
  for (int i = 1; i < v.size(); i++) {
    fast_print(' ');
    fast_print(v[i]);
  }
}
template <class T>
void fast_print(const vector<vector<T>> &v) {
  if (v.empty()) return;
  fast_print(v[0]);
  for (int i = 1; i < v.size(); i++) {
    fast_print('\n');
    fast_print(v[i]);
  }
}
template <class T>
void fast_print(const T &v) {
  for (const auto &first : v) {
    fast_print(first);
    fast_print(' ');
  }
}
using namespace std;
namespace smart_io {
string print_start = "";
string sep = " ";
bool first_print = false;
void precall_print() {
  fast_print(print_start);
  print_start = "\n";
  first_print = true;
}
void _print(deque<string>) {}
template <class T, class... Args>
void _print(deque<string> names, T elem, Args... args) {
  if (!first_print) {
    fast_print("\n");
  } else {
    first_print = false;
  }
  fast_print(names.front());
  fast_print(" = ");
  fast_print(elem);
  names.pop_front();
  _print(names, args...);
}
}  // namespace smart_io
template <class T>
ostream &operator,(ostream &os, const T &object) {
  if (!smart_io::first_print) {
    fast_print(smart_io::sep);
  } else {
    smart_io::first_print = false;
  }
  fast_print(object);
  return os;
}
template <class T>
istream &operator,(istream &is, T &object) {
  fast_scan(object);
  return is;
}
namespace escape__from__random__aetuhoetnuhshe {
using namespace std::chrono;
mt19937 rng(duration_cast<milliseconds>(system_clock::now().time_since_epoch())
                .count());
uniform_real_distribution<> prob_dist(0.0, 1.0);
};  // namespace escape__from__random__aetuhoetnuhshe
namespace typedefs {}
namespace numbers_operation {
template <class T>
T floor_mod(T a, T b) {
  if (a >= 0 && b >= 0) return a % b;
  if (a <= 0 && b <= 0) return a % b;
  return abs(b) - (abs(a) % abs(b));
}
}  // namespace numbers_operation
using namespace numbers_operation;
using namespace typedefs;
using namespace escape__from__random__aetuhoetnuhshe;
int n, h, m;
struct Bord {
  int l, r, bar, c;
};
const int N = 52;
int dp[N][N][N][N];
int up[N];
vector<Bord> bords;
signed main(signed argc, char *argv[]) {
  for (int a = 0; a < (N); a++)
    for (int b = 0; b < (N); b++)
      for (int c = 0; c < (N); c++)
        for (int d = 0; d < (N); d++) dp[a][b][c][d] = -1e9;
  cin, n, h, m;
  bords.resize(m);
  for (int i = 0; i < (m); i++) {
    cin, bords[i].l, bords[i].r, bords[i].bar, bords[i].c;
    bords[i].l--;
  }
  for (int i = 0; i < N; i++) {
    for (int first = 0; first < N; first++) {
      for (int second = 0; second < N; second++) {
        dp[i][i][first][second] = 0;
      }
    }
  }
  for (int l = 1; l <= n; l++) {
    for (int i = 0; i < n - l + 1; i++) {
      int r = i + l;
      for (int first = 0; first < (h + 1); first++) {
        for (int second = 0; second < (h + 1); second++) {
          memset(up, 0, sizeof up);
          if (first < second) {
            if (second > 0)
              dp[i][i + l][first][second] = dp[i][i + l][first][second - 1];
          } else {
            if (first > 0)
              dp[i][i + l][first][second] = dp[i][i + l][first - 1][second];
          }
          int cur = max(first, second);
          for (Bord bord : bords) {
            if (cur > bord.bar && i <= bord.l && bord.r <= i + l) {
              up[bord.l] += bord.c;
              up[bord.r] -= bord.c;
            }
          }
          int plus = 0;
          for (int j = i; j < r; j++) {
            int sub = cur * cur;
            plus += up[j];
            dp[i][i + l][first][second] =
                max(dp[i][i + l][first][second],
                    dp[i][j][first][cur] + dp[j + 1][i + l][cur][second] + sub -
                        plus);
          }
        }
      }
    }
  }
  smart_io::precall_print();
  cout, dp[0][n][h][h];
}
