#include<cstdio>
#define maxn 50005
#define maxl 1000007
using namespace std;
int a[maxl],i,j,n,x,y,z,t;
void maxf(int &a,int b)
{ if(a==0) { a=b;
			 return;
		   }
  if(a>b) a=b;
}
long long rez;
int main()
{ freopen("gardieni.in","r",stdin);
  freopen("gardieni.out","w",stdout);
  scanf("%d %d",&n,&t);
  for(i=1;i<=n;++i) { scanf("%d %d %d",&x,&y,&z);
				      for(j=x;j<=y;++j) maxf(a[j],z);
					}
  for(i=1;i<=t;++i) rez+=a[i];
  printf("%lld\n",rez);
  fclose(stdin);
  fclose(stdout);
  return 0;
}