ll n, c;
    cin>>n>>c;
    vector<pair<ll, ll> > v;
    for(int i=0; i<n; ++i)
    {
        ll a,b,p;
        cin>>a>>b>>p;
        v.push_back({a, p});
        v.push_back({b+1, -p});
    }
    sort(v.begin(), v.end());
    ll ans = 0;
    ll accum = 0;
    for(int i=0; i<2*n; ++i)
    {
        ll a = v[i].first, p = v[i].second;
        accum += p;
        if(i+1<2*n)
        {
            ans += min(accum*(v[i+1].first-a), c*(v[i+1].first-a));
        }
    }
    cout<<ans<<endl;