#include <fstream>

using namespace std;

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

const int max_size = 1e6 + 1, INF = (1 << 20) + 1;

int ans[max_size];

int main ()
{
    int m, n;
    in >> m >> n;
    for (int i = 1; i <= n; i++)
    {
        ans[i] = INF;
    }
    while (m--)
    {
        int x, y, c;
        in >> x >> y >> c;
        for (int i = x; i <= y; i++)
        {
            ans[i] = min(ans[i], c);
        }
    }
    int rez = 0;
    for (int i = 1; i <= n; i++)
    {
        rez += ans[i];
    }
    out << rez;
    in.close();
    out.close();
    return 0;
}