#include <fstream>
#include <algorithm>
using namespace std;

long n,T,t[1000001];

ofstream out("gardieni.out");
inline void citire()
{
	long a,b,c;
	long i,j;
	ifstream in("gardieni.in");
	in>>n>>T;
	for(i=1;i<=n;i++)
	{
		
		in>>a>>b>>c;
		for(j=a;j<=b;j++)
			if(t[j]>c || !t[j])
				t[j]=c;
	}

	long s=0;
	for(i=1;i<=T;i++)
		s += t[i];
	out<<s;

}

int main()
{
	citire();
	return 0;
}