#include <stdio.h>
#include <vector>
using namespace std;

#define DIM 1000002
#define MAX 100000017

vector <int> timp (DIM, MAX);
int n, T, i, j;
int a, b, c;
long long suma;

int main()
{
    FILE *f = fopen ("gardieni.in","r");
    FILE *g = fopen ("gardieni.out","w");
    fscanf (f,"%d %d", &n, &T);

    for (i=1; i<=n; ++i)
    {
        fscanf (f,"%d %d %d", &a, &b, &c);
        for (j=a; j<=b; ++j)
            if (timp[j] > c)
                timp[j] = c;
    }

    for (i=1; i<=T; ++i)
        suma += timp[i];
        //printf ("%lld ", timp[i]);

    fprintf (g,"%lld", suma);

    fclose(g);
    fclose(f);
    return 0;
}