#include <fstream>
#define nmax 1000100
using namespace std;

int N,T,A[nmax];
long long Answer;

int main () {

    int i,j,X,Y,C;
    ifstream in("gardieni.in");
    ofstream out("gardieni.out");

    in>>N>>T;

    for(i=1;i<=N;i++) {

        in>>X>>Y>>C;

        for(j=X;j<=Y;j++)
            if(!A[j] || A[j]>C)
                A[j]=C;

        }

    for(i=1;i<=T;i++)
        Answer+=A[i];

    out<<Answer<<'\n';

    in.close();
    out.close();

    return 0;

}