#include <bits/stdc++.h>
#define fi first
#define se second
#define pii pair <int , int>
#define arr3 array <int , 3>
/*
+ array limit ???
+ special case ??? n = 1?
+ time limit ???
*/
using namespace std;
const int INF = 1e18 + 7;
const int maxn = 3e5;
struct Fenwick_Max
{
int tree[maxn + 4];
void update(int pos , int val)
{
while(pos <= maxn)
{
tree[pos] = max(tree[pos] , val);
pos += (pos & (-pos));
}
}
int get(int pos)
{
int res = 0;
while(pos > 0)
{
res = max(res , tree[pos]);
pos -= (pos & (-pos));
}
return res;
}
};
Fenwick_Max bitx;
Fenwick_Max bity;
int n; arr3 a[maxn];
map <int , vector <pii>> mp;
vector <int> val;
void compress()
{
for(int i = 1; i <= n; i++)
{
val.push_back(a[i][0]);
val.push_back(a[i][1]);
}
sort(val.begin() , val.end());
val.erase(unique(val.begin(), val.end()), val.end());
for(int i = 1; i <= n; i++)
{
a[i][0] = upper_bound(val.begin() , val.end() , a[i][0]) - val.begin();
a[i][1] = upper_bound(val.begin() , val.end() , a[i][1]) - val.begin();
mp[a[i][2]].push_back({a[i][0] , a[i][1]});
}
}
void solve()
{
cin >> n;
for(int i = 1; i <= n; i++)
{
cin >> a[i][0] >> a[i][1] >> a[i][2];
}
compress();
int max_x = 0 , max_y = 0 , ans = -1;
for(pair <int , vector <pii>> piv: mp)
{
int z = piv.fi;
vector <pii> vp = piv.se;
for(pii tmp: vp)
{
int x = tmp.fi;
int y = tmp.se;
if(x < max_x && y < max_y)
{
ans = max(ans , z + val[max_x - 1] + val[max_y - 1]);
}
}
for(pii tmp: vp)
{
int x = tmp.fi;
int y = tmp.se;
if(bitx.get(x - 1) > y)
{
max_x = max(max_x , x);
max_y = max(max_y , bitx.get(x - 1));
}
if(bity.get(y - 1) > x)
{
max_x = max(max_x , bity.get(y - 1));
max_y = max(max_y , y);
}
bitx.update(x , y);
bity.update(y , x);
}
}
cout << ans << '\n';
}
signed main()
{
ios_base::sync_with_stdio(false);
cin.tie(0); cout.tie(0);
solve();
return 0;
}
