#include <bits/stdc++.h>
using namespace std;
#define int long long
signed main(){
srand((unsigned)time(NULL));
ios::sync_with_stdio(false);
std::cin.tie(0);
int N;
cin>>N;
vector<int> A(N);
vector<pair<int,int>> S(N);
for(int i=0;i<N;i++){
cin>>A[i];
S[i] = {A[i],i};
}
sort(S.rbegin(),S.rend());
int ans = 0;
for(auto [a,t]:S){
if(clock() > CLOCKS_PER_SEC) break;
{
multiset<int> s;
int ma = 0;
for(int i=t+2;i<N;i++){
if((i-t)%2 == 0) ma = max(ma,A[(i+t)/2]);
ans = max(ans,a+ma+A[i]);
}
ma = 0;
if(t) s.insert(A[t-1]);
for(int i=t-2;i>=0;i--){
ans = max(ans,a+ma+*s.rbegin());
s.insert(A[i]);
if((t-i)%2 == 0) s.erase(s.find(A[i]));
}
}
{
int ind = N-1, ma = -1e18;
for(int i=0;i<t;i++){
while(t-i <= ind-t){
ma = max(ma,A[ind]);
ind--;
}
ans = max(ans,A[i]+A[t]+ma);
}
}
}
for(int l=0;l<N-2;l++){
int ma = 0;
for(int r=l+2;r<=min(N-1,l+300);r++){
if((r-l)^1) ma = max(ma,A[(l+r)/2]);
ans = max(ans,ma+A[l]+A[r]);
}
}
cout<<ans<<endl;
}
