#include <fstream>

using namespace std;

ifstream cin("gardieni.in");
ofstream cout("gardieni.out");
int a, b, c, n, i, j, t, v[1000010];
long long s;
int main()
{

    cin>>n>>t;
    for(i=1;i<=n;++i)
        {
            cin>>a>>b>>c;
            for(j=a;j<=b;++j)
                if(v[j]>c || v[j]==0)
                    v[j]=c;
        }
    for(i=1;i<=t;++i)
        s+=v[i];
    cout<<s<<"\n";
    return 0;
}