#include <bits/stdc++.h>
using namespace std;
constexpr int BASE = 1 << 18;
struct cord{
int x, y, z;
};
map<int, int> mapa[2];
int translate[2][BASE];
pair<int, int> TREE[2][BASE<<1];
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;
}
for(int i = 1; i <= n; i++){
INPUT[i].x = mapa[0][INPUT[i].x];
INPUT[i].y = mapa[1][INPUT[i].y];
}
}
pair<int, int> merge(pair<int, int> a, pair<int, int> b){
if(a.first != b.first)
return max(a, b);
else if(a.second < b.second)
return a;
return b;
}
void update(int v, int val, int t){
v += BASE;
TREE[t][v] = max(TREE[t][v], {val, v-BASE});
v/=2;
while(v > 0){
int l = 2*v, r = 2*v+1;
TREE[t][v] = merge(TREE[t][l], TREE[t][r]);
v/=2;
}
}
pair<int, int> query(int a, int b, int t){
a += BASE - 1;
b += BASE + 1;
pair<int, int> res = {0, 0};
while(a/2 != b/2){
if(a%2 == 0) res = merge(res, TREE[t][a+1]);
if(b%2 == 1) res = merge(res, TREE[t][b-1]);
a/=2; b/=2;
}
return res;
}
bool check(int mid, cord a){
pair<int, int> maxX = query(a.y, mid, 0);
if(maxX.first <= a.x) return true;
pair<int, int> maxY = query(a.x, maxX.first - 1, 1);
if(maxY.first <= maxX.second) return false;
return true;
}
int BS(cord a){
int l = a.y +1, r = BASE - 1, mid;
while(l < r){
mid = (l +r)/2;
if(check(mid, a)) l = mid+1;
else r = mid;
}
if(!check(l, a)) l--;
pair<int, int> maxX = query(a.y, l, 0);
//cout << "maxX " << maxX.first << "\n";
if(maxX.first <= a.x) return -1;
pair<int, int> maxY = query(a.x, maxX.first - 1, 1);
if(maxY.first <= maxX.second) return -1;
//cout << "maxY " << maxY.first << "\n";
return a.z + translate[0][maxX.first] + translate[1][maxY.first];
//return 0;
}
int solve(){
int res = -1;
for(int i = 1; i <= n; i++){
//cerr << "x " << INPUT[i].x << " y " << INPUT[i].y << " z " << INPUT[i].z << "\n";
res = max(res, BS(INPUT[i]));
update(INPUT[i].y, INPUT[i].x, 0);
update(INPUT[i].x, INPUT[i].y, 1);
}
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];
}
scale();
sort(INPUT + 1, INPUT + n + 1, cmp);
cout << solve() << "\n";
}
