Horizon

#include <bits/stdc++.h>

typedef unsigned long long ll;
using namespace std;

#define all(x) x.begin(), x.end()
#define f(i,a,b) for(int i = (a); i <= (b); i++)
#define fd(i,a,b) for(int i = (a); i >= (b); i--)
#define mp make_pair
#define faster_io() ios_base::sync_with_stdio(false)
#define pb push_back
#define pii pair<int,int>
#define SZ(x) ((int)x.size())
#define vii vector<pair<int,int>>

const int INF = 1000000007;
const ll INFLL = 100000000000000000ll;
const ll MOD = 1000000007;

// ----------------------------------------------------------------------------------------------------------

int N;
multiset<int,greater<int>> S;
multiset<pair<pii,int>> Events;

int main()
{
    cin >> N;
    f(i,1,N)
    {
        int l,r,h;
        scanf("%d %d %d", &l, &r, &h);
        Events.insert({{l,0},h});
        Events.insert({{r,1},h});
    }

    int last = 0;
    ll ans = 0;

    for(pair<pii,int> p : Events)
    {
        int x = p.first.first, t = p.first.second, h = p.second;
        if(!S.empty())
        {
            ll h = *S.begin();
            ans += h * (x-last);
        }

        if(t==0) S.insert(h);
        else
        {
            auto it = S.find(h);
            S.erase(it);
        }

        last = x;
    }

    cout << ans;
}