#include <iostream>
#include <fstream>
#include <climits>

using namespace std;

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

int main()
{
    long int n, i, t, j, mn=INT_MIN, jj, cost=0;
    struct segment {
        int inc, sf, lg;
    } S[50005] ;
    f>>n>>t;
    for (i=0; i<n; i++) f>>S[i].inc>>S[i].sf>>S[i].lg;
    for (i=1; i<=t; i++) {
        for (j=0, mn=INT_MAX; j<n; j++)
            if (S[j].inc<=i && S[j].sf>=i)
                if (S[j].lg<mn) { mn=S[j].lg; jj=j; }
        cost+=S[jj].lg;
    }
    g<<cost;
    return 0;
}