//Include
#include <fstream>
using namespace std;

//Constante
const int MAX_T = (int)1e6+1;
const int oo = (int)15e8;

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

int n, t;
int iLeft, iRight, val;
int sum;
int v[MAX_T];

//Main
int main()
{
	in >> n >> t;
	for(int i=1 ; i<=t ; ++i)
		v[i] = oo;
	
	for(int i=1 ; i<=n ; ++i)
	{
		in >> iLeft >> iRight >> val;
		for(int i=iLeft ; i<=iRight ; ++i)
			v[i] = min(v[i], val);
	}
	
	for(int i=1 ; i<=t ; ++i)
		sum += v[i];
	
	out << sum;
	
	in.close();
	out.close();
	return 0;
}