#include <bits/stdc++.h>
using namespace std;
#define f first
#define s second
const int N = 2e5 + 69;
const int A = 550;
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];
signed main() {
ios::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
int tt = 1;
//cin >> tt;
while (tt--) {
cin >> n;
for (int i = 1;i <= n;i++)
cin >> a[i] >> b[i] >> c[i];
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 ans = -1;
for (int i = 1;i <= n;i++) {
for (int j = a[i] + 1;j < A;j++) {
if (mn[j][b[i] - 1] < d[j - 1][b[i] - 1] && d[j - 1][b[i] - 1] > c[i]) {
ans = max(ans, b[i] + j + d[j - 1][b[i] - 1]);
}
}
}
cout << ans << '\n';
}
return 0;
}
