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

double pret[1000001];

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

    f>>N>>T;
     
    for(i=1;i<=N;i++)
       {f>>a>>b>>c;
        //costul timpilor dintre a si b;
        for(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;
}