#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
//#include<bits/extc++.h>
//__gnu_pbds
vector<int> Y;
vector<int> Z;
vector<int> X;
vector<int> ordery;
vector<int> rg;
struct seg{
vector<int> arr;
int n;
void init(int S){
n = S;
arr.resize(2*S);
}
void chmax(int l,int r,int v){
l+=n;r+=n;
while(l<r){
if(l&1){arr[l] = max(arr[l],v);l++;}
if(r&1){r--;arr[r] = max(arr[r],v);}
l>>=1;r>>=1;
}
}
int get(int ind){
ind+=n;
int ans = 0;
while(ind){
ans = max(ans,arr[ind]);
ind>>=1;
}
return ans;
}
} sgt;
int P = -1;
map<int,int> posP;
int n;
void add(int ind){
int k = ordery[ind];
sgt.chmax(rg[k],n,Z[ind]);
if(posP.size()==0){
if(k>P){
if(sgt.get(k)>Z[ind]) P=k;
else posP[Y[ind]]=ind;
}
return;
}
auto it = posP.upper_bound(Y[ind]);
if(it==posP.end() || Z[it->second]>=Z[ind]){
int g = it->second;
--it;
while(posP.begin()->second!=g){
if(Z[it->second]>=Z[ind]) posP.erase(it--);
else break;
}
posP[Y[ind]]=ind;
if(sgt.get(k)>Z[ind]){
P = k;
while(posP.size() && ordery[posP.begin()->second]<=P){
posP.erase(posP.begin());
}
}
}else{
int g = it->second;
while(posP.size() && posP.begin()->second!=g){posP.erase(posP.begin());}
while(posP.size() && sgt.get(ordery[posP.begin()->second])>Z[posP.begin()->second]){
P=ordery[posP.begin()->second];
posP.erase(posP.begin());
}
}
}
int main(){
ios_base::sync_with_stdio(0),cin.tie(0),cout.tie(0);
cin>>n;
X.resize(n);
Y.resize(n);
Z.resize(n);
vector<int> w(n);
sgt.init(n);
for(int i=0;i<n;i++) cin>>X[i]>>Y[i]>>Z[i];
vector<int> order(n);
vector<int> oty(n);
ordery.resize(n);
for(int i=0;i<n;i++) order[i]=i;
sort(order.begin(),order.end(),[&](const int a,const int b){return (Y[a]==Y[b])?(Z[a]>Z[b]):(Y[a]<Y[b]);});
for(int i=0;i<n;i++){
oty[i]=order[i];
ordery[order[i]]=i;
}
rg.resize(n,0);
int head = 0;
for(int i=0;i<n;i++){
while(head<n && Y[order[head]]<=Y[order[i]]) head++;
rg[i]=head;
}
sort(order.begin(),order.end(),[&](const int a,const int b){return (X[a]==X[b])?(Y[a]>Y[b]):(X[a]<X[b]);});
int prevx = -1;
queue<int> tobeadd;
int ans = -1;
for(auto i : order){
if(X[i]!=prevx){
while(tobeadd.size()){
add(tobeadd.front());
tobeadd.pop();
}
}
if(P>=0 && Y[oty[P]]>Y[i] && sgt.get(P)>Z[i]){
ans = max(ans,X[i]+Y[oty[P]]+sgt.get(P));
}
prevx = X[i];
tobeadd.push(i);
}
cout<<ans<<"\n";
return 0;
}
