#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e6 + 5;
int t, n, h, m, a[maxn], x;
int sum;
int main() {
  ios::sync_with_stdio(0);
  cin >> n >> h >> m;
  for (int i = 1; i <= n; ++i) a[i] = h;
  for (int i = 0; i < m; ++i) {
    int l, r, w;
    cin >> l >> r >> w;
    for (int i = l; i <= r; ++i) {
      a[i] = min(a[i], w);
    }
  }
  long long ac = 0;
  for (int i = 1; i <= n; ++i) {
    ac += a[i] * a[i];
  }
  cout << ac << endl;
  return 0;
}
