#include <cstdio>
#include <cstring>
#include <algorithm>
#include <vector>
#define x first
#define y second
#define pb push_back
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
const int n = 4e3 + 10;
int dvade[n][n];
vector<int> x, y, z;
void solve(vector<pair<pii, int>> v) {
memset(dvade, -1, sizeof(dvade));
int n = v.size();
for(auto &i : v) {
x.pb(i.x.x);
y.pb(i.x.y);
z.pb(i.y);
}
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(auto &i : v) {
int a = i.x.x, b = i.x.y, c = i.y;
int j = lower_bound(x.begin(), x.end(), a) - x.begin() + 1;
int k = lower_bound(y.begin(), y.end(), b) - y.begin() + 1;
// printf("%d %d %d %d %d\n", a, b, c, j, k);
dvade[j][k] = max(dvade[j][k], c);
}
for(int i = 0; i <= n; ++i) {
for(int j = 0; j <= n; ++j) {
if(i) dvade[i][j] = max(dvade[i - 1][j], dvade[i][j]);
if(j) dvade[i][j] = max(dvade[i][j], dvade[i][j - 1]);
}
}
int ans = -1;
for(auto &i : v) {
for(auto &j : v) {
int a = i.x.x, b = i.x.y, c = i.y;
int a_ = j.x.x, b_ = j.x.y, c_ = j.y;
int ind1 = lower_bound(x.begin(), x.end(), a) - x.begin();
int ind2 = lower_bound(y.begin(), y.end(), a) - y.begin();
if(a > a_ && b < b_ && c < dvade[ind1][ind2] && c_ < dvade[ind1][ind2] && dvade[ind1][ind2] != -1) {
ans = max(ans, a + b_ + dvade[ind1][ind2]);
}
}
}
printf("%d\n", ans);
}
int main() {
int n;
scanf("%d", &n);
vector<pair<pii, int>> v;
for(; n--; ) {
int x, y, z;
scanf("%d%d%d", &x, &y, &z);
v.pb({{x, y}, z});
}
sort(v.begin(), v.end());
v.erase(unique(v.begin(), v.end()), v.end());
solve(v);
return 0;
}
