#include <cstdio>
#include <fstream>

using namespace std;

#define m 1000001

int T[m];
int a,b,c,n,t;

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

int solve () {
	
	int s=T[1];
	for(int i=2;i<=t;++i)
	s+=T[i];
	
	return s;} 	

void write (int s){
	
	freopen ("gardieni.out","w",stdout);
	printf("%d\n",s);
	
	}

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