#include <bits/stdc++.h>
using namespace std;
#define f first
#define s second
const int N = 2e5 + 69;
const int A = 4010;
const int inf = 1e9;
int n, a[N], b[N], c[N], d[A][A];
int gmx[A][A], gmn[A][A], mn[A][A];
map<int, int> ca, cb, cc;
signed main() {
ios::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
int tt = 1;
//cin >> tt;
while (tt--) {
cin >> n;
vector<int> x, y, z;
for (int i = 1;i <= n;i++) {
cin >> a[i] >> b[i] >> c[i];
x.push_back(a[i]);
y.push_back(b[i]);
z.push_back(c[i]);
}
sort(x.begin(), x.end());
x.erase(unique(x.begin(), x.end()), x.end());
sort(y.begin(), y.end());
y.erase(unique(y.begin(), y.end()), y.end());
sort(z.begin(), z.end());
z.erase(unique(z.begin(), z.end()), z.end());
for (int i = 1;i <= n;i++) {
auto u = lower_bound(x.begin(), x.end(), a[i]) - x.begin() + 1;
ca[u] = a[i];
a[i] = u;
u = lower_bound(y.begin(), y.end(), b[i]) - y.begin() + 1;
cb[u] = b[i];
b[i] = u;
u = lower_bound(z.begin(), z.end(), c[i]) - z.begin() + 1;
cc[u] = c[i];
c[i] = u;
}
for (int i = 0;i < A;i++) {
for (int j = 0;j < A;j++) {
gmn[i][j] = inf;
gmx[i][j] = -inf;
d[i][j] = -inf;
mn[i][j] = inf;
}
}
for (int i = 1;i <= n;i++) {
gmx[a[i]][b[i]] = max(c[i], gmx[a[i]][b[i]]);
gmn[a[i]][b[i]] = min(c[i], gmn[a[i]][b[i]]);
}
for (int i = 1;i < A;i++) {
for (int j = 1;j < A;j++) {
d[i][j] = max({d[i][j - 1], d[i - 1][j], gmx[i][j]});
mn[i][j] = min(mn[i][j - 1], gmn[i][j]);
}
}
int R;
if (n > 4000)
R = 1000;
else
R = A - 1;
int ans = -1;
for (int i = 1;i <= n;i++) {
for (int j = R;j > a[i];j--) {
if (mn[j][b[i] - 1] < d[j - 1][b[i] - 1] && d[j - 1][b[i] - 1] > c[i]) {
ans = max(ans, cb[b[i]] + ca[j] + cc[d[j - 1][b[i] - 1]]);
break;
}
}
}
cout << ans << '\n';
}
return 0;
}
