#include<iostream>
#include<fstream>
#include<math.h>
using namespace std;
ifstream f("gardieni.in");
ofstream g("gardieni.out");

unsigned long int  pret[1000001],N,T;


int main()
{  unsigned long int suma=0,i,a,b,c;
         

    f>>N>>T;
     
    for(i=1;i<=N;i++)
       {f>>a>>b>>c;
        //costul timpilor dintre a si b;
        for(int j=a;j<=b;j++)
         if(c<pret[j])pret[j]=c;
           else if(pret[j]==0)pret[j]=c;
       }
       
       //calculam suma totala
       for(i=1;i<=T;i++)
        suma+=pret[i];
    g<<suma;
   
   return 0;
}