#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;
 
}