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

using namespace std;

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

int main()
{
    int N,t,i,j,jj,mn=INT_MAX;
    long long int T,SUMA=0;
    struct segment{
        int a,b,c;}S[50006];

    f>>N>>T;
    for(i=1;i<=N;i++)f>>S[i].a>>S[i].b>>S[i].c;
    for(i=1;i<=T;i++){
        mn=INT_MAX;
    for(j=1;j<=T;j++)
        if(S[j].a<=i && S[j].b>=i)
            if(S[j].c<mn){
                mn=S[j].c;
                jj=j;
            }
        SUMA=SUMA+S[jj].c;


}

    g<<SUMA;

    f.close();
    g.close();
    return 0;
}