#include<fstream>

using namespace std;

#define NMAX 1000100
const int MN=1<<29;

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

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

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