#include <fstream>
using namespace std;

int n, t, x, y, c;
int v[1000100];
long long sol;
int main()
{
    ifstream f("gardieni.in");
    ofstream g("gardieni.out");

    f >> n >> t;
    for (int i = 1; i <= n; ++i)
    {
        f >> x >> y >> c;
        for (int j = x; j <= y; ++j)
            if (v[j] > c || v[j] == 0) v[j] = c;
    }

    for (int i = 1; i <= t; ++i)
        sol = sol + v[i];

    g << sol << '\n';
    g.close();
    return 0;
}