#include <iostream>
#include <fstream>
#include <algorithm>
using namespace std;
int n,t,T[1000000];
struct str{int a,b,c;} A[50005];
void citire()
{
    ifstream fin ("gardieni.in");
    fin >>n>>t;
    for (int i=1;i<=n;i++)
        fin>>A[i].a>>A[i].b>>A[i].c;
    fin.close();
}
int main ()
{
    long long s=0;
    ofstream fout("gardieni.out");
    citire();
    for (int i=1;i<=n;i++)
        for (int j=A[i].a;j<=A[i].b;j++)
                if (T[j]==0 || T[j]>A[i].c)
                    T[j]=A[i].c;
    for (int i=1;i<=t;i++)
            s+=T[i];
    fout<<s;
    return 0;
}