#include<fstream>
#define NMAX 51000

using namespace std;

const int MN=16<<26;

ifstream in("gardieni.in");
ofstream out("gardieni.out");

int main()
{
    int n,t,v[NMAX],a,b,c,S=0;
    in>>n>>t;
    for (int i=1;i<=t;i++)
      v[i]=MN;

    for (int i=1;i<=n;i++)
    {
        in>>a>>b>>c;
        for (int j=a;j<=b && j<=t;j++)
         v[j]=min(v[j],c);
    }
    
    for (int i=1;i<=t;i++)   
     S+=v[i];
    
    out<<S;
    return 0;
}