#include <iostream>
#include <fstream>
using namespace std;
ifstream in("gardieni.in");
ofstream out("gardieni.out");

int main() {
	long int n, t, v[1000001];
	in >> n >> t;
	for (long int i = 0; i < n;i++) {
        long int a,b,c;
		in >> a >> b >> c;
		for (long int j = a; j <= b; j++)
			if ((v[j] == 0) || (v[j] > c))
				v[j] = c;
	}
	long long int s=0;
	for (long int i = 1; i <= t; i++)
		s += v[i];
	out<<s;
	return 0;
}