#include <fstream>

using namespace std;

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

long n, t, a, b, c, i, j, v[1000100];
long long s = 0;

int main ()
{

    f >> n >> t;

    for (i = 1; i <= n; ++i)
    {
        f >> a >> b >> c;
        for (j = a; j <= b; ++j)
        {
            if(v[j] == 0 || v[j] > c)
                v[j] = c;
        }
    }

    for (i = 1; i <= t; ++i)
    {
        s += v[i];
    }

    g << s;
}