#include "bits/extc++.h"
using namespace std;
template <typename T>
void dbgh(const T& t) {
cerr << t << endl;
}
template <typename T, typename... U>
void dbgh(const T& t, const U&... u) {
cerr << t << " | ";
dbgh(u...);
}
#ifdef DEBUG
#define dbg(...) \
cerr << "L" << __LINE__ << " [" << #__VA_ARGS__ << "]" \
<< ": "; \
dbgh(__VA_ARGS__)
#else
#define cerr \
if (false) \
cerr
#define dbg(...)
#endif
#define endl "\n"
#define long int64_t
#define sz(x) int((x).size())
const int maxn = 150'005;
struct DS1 {
set<pair<int, int>> s;
void insert(int x, int y) {
auto it = s.upper_bound({x, 0});
if (it != s.begin()) {
if (prev(it)->second >= y) {
return;
}
}
while (it != s.end() && y >= it->second) {
it = s.erase(it);
}
s.emplace_hint(it, x, y);
}
int query(int x) const {
auto it = s.lower_bound({x, 0});
if (it == s.begin()) {
return -1;
}
return (--it)->second;
}
};
struct DS2 {
DS1 ds;
void insert(int x, int y) {
ds.insert(y, x);
}
int query(int y) const {
return ds.query(y);
}
};
struct chash {
uint64_t operator()(uint64_t x) const {
x ^= x << 11;
x ^= x >> 9;
x ^= x >> 7;
return x;
}
};
struct Bit1 {
__gnu_pbds::gp_hash_table<int, int, chash> v;
void insert(int ind, int x) {
ind++;
while (ind <= maxn) {
v[ind] = max(v[ind], x);
ind += ind & -ind;
}
}
int query(int ind) const {
int ans = -1;
while (ind) {
auto it = v.find(ind);
if (it != v.end()) {
ans = max(ans, it->second);
}
ind -= ind & -ind;
}
return ans;
}
};
struct DS3 {
Bit1 v[maxn + 1];
void insert(int ind, int y, int val) {
ind = maxn - ind;
y = maxn - y;
ind++;
while (ind <= maxn) {
v[ind].insert(y, val);
ind += ind & -ind;
}
}
int query(int ind, int y) const {
ind = maxn - ind;
y = maxn - y;
int ans = -1;
while (ind) {
ans = max(ans, v[ind].query(y));
ind -= ind & -ind;
}
return ans;
}
};
struct Comp {
vector<int> comp;
Comp(int n, array<int, 3> arr[], int ind) : comp(n) {
for (int i = 0; i < n; i++) {
comp[i] = arr[i][ind];
}
sort(begin(comp), end(comp));
comp.erase(unique(begin(comp), end(comp)), comp.end());
}
int operator[](int ind) const {
return int(lower_bound(begin(comp), end(comp), ind) - comp.begin());
}
};
DS1 ds1;
DS2 ds2;
DS3 ds3;
void solve() {
int n;
cin >> n;
array<int, 3> arr[n];
for (auto& [x, y, z] : arr) {
cin >> x >> y >> z;
}
sort(arr, arr + n);
Comp xs(n, arr, 1), ys(n, arr, 2);
int ans = -1;
for (int i = 0; i < n;) {
int start = i;
for (; i < n && arr[start][0] == arr[i][0]; i++) {
auto& [z, x, y] = arr[i];
int cur = ds3.query(xs[x], ys[y]);
if (cur != -1) {
ans = max(ans, z + cur);
}
}
for (int j = start; j < i; j++) {
auto& [_, x, y] = arr[j];
int ly = ds1.query(x);
if (ly > y) {
ds3.insert(xs[x], ys[ly], x + ly);
}
int rx = ds2.query(y);
if (rx > x) {
ds3.insert(xs[rx], ys[y], rx + y);
}
ds1.insert(x, y);
ds2.insert(x, y);
}
}
cout << ans << endl;
}
int main() {
cin.tie(nullptr);
ios_base::sync_with_stdio(false);
cin.exceptions(ios::failbit);
solve();
}
