#include <fstream>
using namespace std;
ifstream f("gardieni.in");
ofstream g("gardieni.out");
long long minn;
int i,j,v[1000001],n,t,a,b,c;
int main()
{
    f>>n>>t;
    for (i=1;i<=n;i++)
    {
        f>>a>>b>>c;
        for (j=a;j<=b;j++)
        {
            if (v[j]>c || v[j]==0)
            {
              v[j]=c;
            }
        }
    }
    for (i=1;i<=t;i++)
    {
      minn=v[i]+minn;
    }
    g<<minn;
    return 0;
}