#include <iostream>
#include <fstream>
#include <vector>

#define min(a, b) ((a) < (b) ? (a) : (b))

int main()
{
  std::ifstream in("gardieni.in");
  int n, t;
  in >> n >> t;
  std::vector<int> v;
  for (int i = 0; i <= t; ++i) {
    v.push_back(1000000000);
  }
  for (int i = 0; i < n; ++i) {
    int a, b, c;
    in >> a >> b >> c;
    for (int j = a; j <= b; ++j) {
      v[j] = min(v[j], c);
    }
  }
  in.close();

  int total = 0;
  for (int i = 1; i <= t; ++i) {
    total += v[i];
  }

  std::ofstream out("gardieni.out");
  out << total << std::endl;
  out.close();
  return 0;
}