#include<fstream>
#define dmax 1000010
#define inf 9999999
using namespace std;

int n,t;
int x,y,z;
int a[dmax];
long long sol;

void actualizare()
{
 int i;
	
 for (i=x; i<=y; i++)
	 a[i] = min(a[i], z);
}

void initializare()
{
 int i;
 
 for (i=1; i<=t; i++)
	 a[i] = inf;
}


void citire()
{
 int i;
 
 ifstream fin("gardieni.in");
 
 fin>>n>>t;
 initializare();
 for (i=1; i<=n; i++)
	 {
	  fin>>x>>y>>z;
	  actualizare();
	 }
 fin.close();
}


void solve()
{
 int i;
	
 for (i=1; i<=t; i++)
	 sol += a[i];
}


void afisare()
{
 ofstream fout("gardieni.out");
 
 fout<<sol;
 
 fout.close();
}

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