#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N=150005;
const int M=4005;
int n,nx,ny,nz;
int x[N],y[N],z[N];
vector<ll> px,py,pz;
pair<int,int> vx[N],vy[N];
int dp[M][M];
ll ans=-1;
int main(){
cin.tie(nullptr)->sync_with_stdio(false);
cin >> n;
for(int i=1;i<=n;i++){
cin >> x[i] >> y[i] >> z[i];
px.emplace_back(x[i]);
py.emplace_back(y[i]);
pz.emplace_back(z[i]);
}
px.emplace_back(-1e18);
py.emplace_back(-1e18);
pz.emplace_back(-1e18);
sort(px.begin(),px.end());
sort(py.begin(),py.end());
sort(pz.begin(),pz.end());
px.erase(unique(px.begin(),px.end()),px.end());
py.erase(unique(py.begin(),py.end()),py.end());
pz.erase(unique(pz.begin(),pz.end()),pz.end());
nx=px.size()-1;
ny=py.size()-1;
nz=pz.size()-1;
z[0]=nz+1;
for(int i=1;i<=n;i++){
x[i]=lower_bound(px.begin(),px.end(),x[i])-px.begin();
y[i]=lower_bound(py.begin(),py.end(),y[i])-py.begin();
z[i]=lower_bound(pz.begin(),pz.end(),z[i])-pz.begin();
dp[x[i]][y[i]]=max(dp[x[i]][y[i]],z[i]);
}
for(int i=1;i<=nx;i++){
for(int j=1;j<=ny;j++){
dp[i][j]=max({dp[i][j],dp[i-1][j],dp[i][j-1]});
}
}
for(int i=1;i<=n;i++){
for(int j=1;j<=n;j++){
if(x[i]<=x[j]||y[i]>=y[j])continue;
int res=dp[x[i]-1][y[j]-1];
if(res>max(z[i],z[j]))ans=max(ans,px[x[i]]+py[y[j]]+pz[res]);
}
}
cout << ans;
}
