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

int main() {
	long int n, t, a, b, c, v[1000000];
	long long s=0;
	in >> n >> t;
	for (long int i = 1; i <= n;i++) {
		in >> a >> b >> c;
		for (long int j = a; j <= b; j++)
			if (v[j] == 0 || v[j] > c)
				v[j] = c;
	}
	for (long int i = 1; i <= t; i++) {
		s += v[i];
	}
	out<<s;
	return 0;
}