#include <bits/stdc++.h>
using namespace std;
constexpr int BASE = 1 << 18;
struct cord{
int x, y, z;
};
map<int, int> mapa[3];
int translate[3][BASE];
int TREE[2][BASE<<1];
pair<int, int> square;
vector<cord> sorted[BASE];
cord INPUT[BASE];
int n;
bool cmp(cord a, cord b){
if(a.z != b.z)
return a.z < b.z;
else if(a.x != b.x)
return a.x < b.x;
return a.y < b.y;
}
void scale(){
int pos = 0;
for(auto it = mapa[0].begin(); it != mapa[0].end(); ++it){
it->second = ++pos;
translate[0][pos] = it->first;
}
pos = 0;
for(auto it = mapa[1].begin(); it != mapa[1].end(); ++it){
it->second = ++pos;
translate[1][pos] = it->first;
}
pos = 0;
for(auto it = mapa[2].begin(); it != mapa[2].end(); ++it){
it->second = ++pos;
translate[2][pos] = it->first;
}
for(int i = 1; i <= n; i++){
INPUT[i].x = mapa[0][INPUT[i].x];
INPUT[i].y = mapa[1][INPUT[i].y];
INPUT[i].z = mapa[2][INPUT[i].z];
}
}
void update(int v, int val, int t){
v += BASE;
while(v > 0){
TREE[t][v] = max(TREE[t][v], val);
v/=2;
}
}
int query(int a, int b, int t){
a += BASE - 1;
b += BASE + 1;
int res = 0;
while(a/2 != b/2){
if(a%2 == 0) res = max(res, TREE[t][a+1]);
if(b%2 == 1) res = max(res, TREE[t][b-1]);
a/=2; b/=2;
}
return res;
}
int check(cord a){
if(a.x >= square.first) return -1;
if(a.y >= square.second) return -1;
return translate[0][square.first] + translate[1][square.second] + translate[2][a.z];
}
void updatesquare(cord a){
int maxX = query(0, a.y-1, 0);
int maxY = query(0, a.x-1, 1);
//jestem wtedy maxymalnym Y
if(maxX > a.x)
square = max(square, {maxX, a.y});
//jestem wtedy maxymalnym X
if(maxY > a.y)
square = max(square, {a.x, maxY});
update(a.y, a.x, 0);
update(a.x, a.y, 1);
}
int solve(){
int res = -1;
for(int i = 1; i < BASE; i++){
for(auto sor : sorted[i])
res = max(res, check(sor));
//cerr << "x " << INPUT[i].x << " y " << INPUT[i].y << " z " << INPUT[i].z << "\n";
for(auto sor : sorted[i])
updatesquare(sor);
}
return res;
}
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
cin >> n;
for(int i = 1; i <= n; i++){
cin >> INPUT[i].x >> INPUT[i].y >> INPUT[i].z;
mapa[0][INPUT[i].x];
mapa[1][INPUT[i].y];
mapa[2][INPUT[i].z];
}
scale();
for(int i = 1; i <= n; i++)
sorted[INPUT[i].z].push_back(INPUT[i]);
cout << solve() << "\n";
}
