#include <iostream>
#include <fstream>
#include <algorithm>
#define INF 2000000000
 
using namespace std;
 
int n, t, a[1000010];
 
inline void Solve()
{
    ifstream f("gardieni.in");
    f>>n>>t;
    int i;
    for(i=1; i<=t; i++)
        a[i] = INF;
    int x, y, z;
    while(n--)
    {
        f>>x>>y>>z;
        for (i=x; i<=y; i++)
            a[i] = min(a[i], z);
    }
    f.close();
    long long sol;
    sol = 0;
    for(i=1; i<=t; i++)
        sol+=a[i];
 
    ofstream g("gardieni.out");
    g<<sol<<"\n";
    g.close();
 
}
 
int main()
{
    Solve();
    return 0;
}