#include <fstream>
#include <iostream>
using namespace std;

const int MAXT = 1000001;
const int inf = (1 << 21);

int ans[MAXT];

int main()
{
    ifstream cin("gardieni.in");
    ofstream cout("gardieni.out");
    int T, N, a, b, c;
    cin >> N >> T;
    for(int i = 1; i <= T; ++i)
      ans[i] = inf;
    for(int i = 1; i <= N; ++i) {
      cin >> a >> b >> c;
      for(int t = a; t <= b; ++t) {
         if(c < ans[t])
               ans[t] = c;
      }
    }
    long long r = 0;
    for(int i = 1; i <= T; ++i) {
      r += ans[i];
    }
    cout << r;
    return 0;
}