#include <iostream>
#include <fstream>
using namespace std;
ifstream in("gardieni.in");
ofstream out("gardieni.out");
struct gardieni {
	long a, b, c; }v[10000];

int main() {
	long n, t, MIN = 50000, s = 0;
	in >> n >> t;
	long long a[t][n];
	for (long i = 1; i <= n; i++)
		in >> v[i].a >> v[i].b >> v[i].c;

	for (long i = 1; i <= n; i++) {
		for (long j = 1; j <= t; j++) {
			a[i][j] = 0;
			if ((v[i].a <= j) && (j <= v[i].b))
				a[i][j] = v[i].c;
		}
	}

	for (long i = 1; i <= t; i++) {
		for (long j = 1; j <= n; j++) {
			if ((a[j][i] < MIN) && (a[j][i] != 0))
				MIN = a[j][i];
			if (j == n) {
				s += MIN;
				MIN = 50000;
			}
		}
	}

	out << s;
    return 0;
}