#include<stdio.h>
#define nmax 1000002
int sol[nmax];
int main()
{
 freopen("gardieni.in","r",stdin);
 freopen("gardieni.out","w",stdout);
 
 int N,T;
 int i,j,solfin=0;
 int a1,a2,a3,a;
 
 scanf("%d%d",&N,&T);
 for(i=1; i<=N; ++i){
          scanf("%d%d%d",&a1,&a2,&a3);
          for(j=a1; j<=a2; ++j){
          a=sol[j];
          if( !a || a>a3 )
          sol[j]=a3;
          }
 }
 
 for(i=1; i<=T; ++i)
 solfin+=sol[i];
 
 printf("%d\n",solfin);
    return 0;
}