#include <fstream>

using namespace std;

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

const int inf= 1<<30;
const int nmax= 50005;
const int tmax= 1000000;

int a[nmax+1], b[nmax+1], c[nmax+1];
int x[tmax+1];

int main(  ) {
    int n, t;
    fin>>n>>t;
    for ( int i= 1; i<=n; ++i ) {
        fin>>a[i]>>b[i]>>c[i];
    }

    for ( int i= 1; i<=t; ++i ) x[i]= inf;
    for ( int i= 1; i<=n; ++i ) {
        for ( int j= a[i]; j<=b[i]; ++j ) {
            x[j]= min(x[j], c[i]);
        }
    }

    int sol= 0;
    for ( int i= 1; i<=t; ++i ) sol= sol+x[i];
    fout<<sol<<"\n";

    return 0;
}