#include <fstream>
#include <algorithm>

#define INF (1 << 21)
#define DIM 1000001

using namespace std;

ifstream fin("gardieni.in");
ofstream fout("gardieni.out");

int n, t;

int dp[DIM];

int main() {

	fin >> n >> t;

	for (int i = 1; i <= t; i++)
		dp[i] = INF;

	for (int i = 1; i <= n; i++) {

		int x, y, cost;

		fin >> x >> y >> cost;

		for (int j = x; j <= y; j++)
			dp[j] = min(dp[j], cost);

	}

	long long result = 0;

	for (int i = 1; i <= t; i++)
		result += dp[i];

	fout << result << "\n";

	return 0;

}

//Trust me, I'm the Doctor!
//Miriam e tare!