#include <bits/stdc++.h>
#define F first
#define S second
#define all(x) x.begin(), x.end()
#define pb push_back
#define FIO ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0)
using namespace std;
typedef long long ll;
typedef pair <ll, ll> pii;
const int N = 4007;
int n;
int a[N], b[N], c[N], sa[N], sb[N], ia[N], f[N][N];
int main () {
FIO;
cin >> n;
vector <int> aa, bb;
for (int i = 0; i < n; i++) {
cin >> a[i] >> b[i] >> c[i];
aa.pb(a[i]);
bb.pb(b[i]);
ia[i] = i;
}
sort(ia, ia+n, [&](int x, int y){return a[x] < a[y];});
sort(all(aa));
sort(all(bb));
aa.erase(unique(all(aa)), aa.end());
bb.erase(unique(all(bb)), bb.end());
for (int i = 0; i < n; i++) {
sa[i] = lower_bound(all(aa), a[i])-aa.begin();
sb[i] = lower_bound(all(bb), b[i])-bb.begin();
}
memset(f, -1, sizeof f);
for (int i = 0; i < n; i++) {
f[sa[i]+1][sb[i]+1] = max(f[sa[i]+1][sb[i]+1], c[i]);
}
for (int i = 0; i <= n; i++) for (int j = 0; j <= n; j++) {
if (i) f[i][j] = max(f[i][j], f[i-1][j]);
if (j) f[i][j] = max(f[i][j], f[i][j-1]);
}
int res = -1;
for (int i = 0; i < n; i++) {
int x = ia[i];
for (int j = 0; j < i; j++) if (a[ia[j]] < a[x] && b[ia[j]] > b[x]) {
int y = ia[j];
if (f[sa[x]][sb[y]] != -1 && f[sa[x]][sb[y]] > max(c[x], c[y])) res = max(res, f[sa[x]][sb[y]]+a[x]+b[y]);
}
}
cout << res;
return 0;
}
