#include<fstream>
#define dmax 1000004
using namespace std;
ifstream in("gardieni.in");
ofstream out("gardieni.out");
long long sir[dmax],c,n,t,a,b,s;
int main()
{	long long i,j;
	in>>n>>t;
	for(i=1;i<=t;i++)
		sir[i]=999999999;
	for(i=1;i<=n;i++)
	{	in>>a>>b>>c;
		for(j=a;j<=b;j++)
			if(c<sir[j])
				sir[j]=c;
	}
	in.close();
	for(i=1;i<=t;i++)
		s+=sir[i];
	out<<s;
	out.close();
	return 0;
}