#include <iostream>
#include <fstream>
#include <algorithm>
using namespace std;
int n,t,nrg,ok,a[1000013],x,y,z;
long long sol;
int main()
{
    fstream f("gardieni.in",ios::in), g("gardieni.out",ios::out);
    f>>n>>t;
    int i,j;
    for (i=1;i<=n;i++)
    {
        f>>x>>y>>z;
        y=min(y,t);
        for(j=x;j<=y;j++)
            if (a[j]==0 || a[j]>z)
                a[j]=z;
    }
    for (i=1;i<=t;i++)
        sol+=a[i];
    g<<sol;
}