#include<fstream>
using namespace std;

int n, T;
int t[1000001];
int a, b, c;
long long suma;

void read();
void write();

int main()
{
	read();
	write();
	return 0;
}

void read()
{
	ifstream fin("gardieni.in");
	fin >> n >> T;
	
	for(int i = 1; i <= n; ++i)
	{
		fin >> a >> b >> c;
		
		for(int j = a; j <= b; j++)
		if( t[j] == 0 || t[j] > c)
			t[j] = c;
	}
	
	fin.close();
}

void write()
{
	ofstream fout("gardieni.out");
	
	for(int i = 1; i <= T; ++i)
		suma += t[i];
	
	fout << suma;
	
	fout.close();
}