#include <fstream.h>

ifstream fin("gardieni.in");
ofstream fout("gardieni.out");

struct sirul{
    int a,b,c;
};

typedef struct sirul sip;
sip sir[50010];
long S,n,t;

void citire()
{
   fin>>n>>t;
     for (int i=0;i<n;i++)
	fin>>sir[i].a>>sir[i].b>>sir[i].c;
   fin.close();
}

int nu(int i,int j)
{
   if (sir[j].a<=i && sir[j].b>=i)
      return 1;
   return 0;
}

int mic(int a,int b)
{
   if (a<b)
      return a;
   return b;
}

void suma()
{
   int min=0;
   for (int i=1;i<=t;i++)
   {
     min=9000000;
       for (int j=0;j<n;j++)
	   if (nu(i,j))
	    min=mic(min,sir[j].c);
   S+=min;
   }
}

int main()
{
   citire();
   suma();
   fout<<S<<"\n";
   fout.close();
   return 0;
}