#include<fstream>

using namespace std;

const char iname[]="gardieni.in";
const char oname[]="gardieni.out";
const int maxt=1000005;

ifstream f(iname);
ofstream g(oname);

int a[maxt],i,n,x,y,j,t;
long long rez;

int main()
{
    f>>n>>t;
    for(i=1;i<=n;++i)
    {
        f>>x>>y>>rez;
        for(j=x;j<=y;++j)
            if(a[j]==0||a[j]>rez)
                a[j]=rez;
    }
    rez=0;
    for(i=1;i<=t;++i)
        rez+=a[i];
    g<<rez<<"\n";
}