#include <fstream>

using namespace std;

ifstream cin ("gardieni.in");
ofstream cout ("gardieni.out");

const int NMAX = 1000000;
const int INF = (1 << 20);

int n, t;
int a, b, c;
long long sum;

int sol[1 + NMAX];

int main() {
  cin >> n >> t;
  for(int i = 1; i <= t; i++)
    sol[i] = INF;
  for(int i = 1; i <= n; i++) {
    cin >> a >> b >> c;
    for(int j = a; j <= b; j++)
      sol[j] = min(sol[j], c);
  }
  for(int i = 1; i <= t; i++)
    sum += sol[i];
  cout << sum;
  return 0;
}