#include <cstdio>

#define DIM 1000010
#define INF 1000000010
using namespace std;

int N, T, X, Y, Z, D[DIM];
long long sol;

int main () {

    freopen ("gardieni.in" ,"r", stdin );
    freopen ("gardieni.out","w", stdout);

    scanf ("%d %d", &N, &T);

    for (int i = 1; i <= T; i ++)
        D[i] = INF;

    for (int i = 1; i <= N; i ++) {
        scanf ("%d %d %d", &X, &Y, &Z);

        for (int j = X; j <= Y; j ++)
            if (D[j] > Z) D[j] = Z;
    }

    for (int i = 1; i <= T; i ++)
        sol += D[i];

    printf ("%lld\n", sol);

    return 0;

}