#include <cstdio>
#include <fstream>

using namespace std;

#define m 1000001

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

inline 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 ();
	
}

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

inline void write (){
	
	ofstream out ("gardieni.out");
	out<<s<<"\n";
	out.close ();
	
	}

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