#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
#define MASK(i) (1LL << (i))
#define GETBIT(mask, i) (((mask) >> (i)) & 1)
#define ALL(v) (v).begin(), (v).end()
ll max(ll a, ll b){return (a > b) ? a : b;}
ll min(ll a, ll b){return (a < b) ? a : b;}
ll gcd(ll a, ll b){
while(a > 0 && b > 0){
if (a > b) a %= b;
else b %= a;
}
return a + b;
}
ll LASTBIT(ll mask){return (mask) & (-mask);}
int pop_cnt(ll mask){return __builtin_popcountll(mask);}
int ctz(ll mask){return __builtin_ctzll(mask);}
int logOf(ll mask){return __lg(mask);}
mt19937_64 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
ll rngesus(ll l, ll r){return l + (ull) rng() % (r - l + 1);}
template <class T1, class T2>
bool maximize(T1 &a, T2 b){
if (a < b) {a = b; return true;}
return false;
}
template <class T1, class T2>
bool minimize(T1 &a, T2 b){
if (a > b) {a = b; return true;}
return false;
}
template <class T>
void printArr(T& container, string separator = " ", string finish = "\n"){
for(auto item: container) cout << item << separator;
cout << finish;
}
template <class T>
void remove_dup(vector<T> &a){
sort(ALL(a));
a.resize(unique(ALL(a)) - a.begin());
}
struct FenwickTree{
int n;
vector<ll> a;
FenwickTree(int _n){
n = _n;
a.resize(n+1);
}
void update(int i, ll v){
while(i <= n){
maximize(a[i], v);
i += LASTBIT(i);
}
}
ll get(int i){
ll ans = 0;
while(i > 0){
maximize(ans, a[i]);
i -= LASTBIT(i);
}
return ans;
}
};
void solve(){
int n; cin >> n;
vector<array<int, 3>> a(n);
for(int i = 0; i < n; ++i) cin >> a[i][0] >> a[i][1] >> a[i][2];
vector<int> X = {0}, Y = {0};
for(int i = 0; i < n; ++i){
X.push_back(a[i][1]);
Y.push_back(a[i][2]);
}
remove_dup(X); remove_dup(Y);
for(int i = 0; i < n; ++i){
a[i][1] = lower_bound(ALL(X), a[i][1]) - X.begin();
a[i][2] = lower_bound(ALL(Y), a[i][2]) - Y.begin();
}
map<int, vector<pair<int, int>>> mp;
for(int i = 0; i < n; ++i) {
mp[a[i][0]].push_back({a[i][1], a[i][2]});
}
int x = X.size() - 1, y = Y.size() - 1;
FenwickTree bit1(x), bit2(y);
int ma_x = 0, ma_y = 0;
ll ans = -1;
for(auto i: mp){
vector<pair<int, int>> cur = i.second;
for(auto j: cur){
if (X[j.first] < ma_x && Y[j.second] < ma_y) {
maximize(ans, i.first + ma_x + ma_y);
}
}
for(auto j: cur){
int cur1 = bit1.get(j.first - 1), cur2 = bit2.get(j.second - 1);
if (cur1 > j.second) {
maximize(ma_x, X[j.first]);
maximize(ma_y, Y[cur1]);
}
if (cur2 > j.first) {
maximize(ma_y, Y[j.second]);
maximize(ma_x, X[cur2]);
}
bit1.update(j.first, j.second);
bit2.update(j.second, j.first);
}
}
cout << ans << "\n";
}
int main(void){
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
clock_t start = clock();
solve();
cerr << "Time elapsed: " << clock() - start << "ms!\n";
return 0;
}
