#include<bits/stdc++.h>
using namespace std;

#define ll long long
#define cl(a) memset(a,0,sizeof a)
#define copy(a,b) copy(begin(a),end(a),begin(b))
#define ld long double
#define dot(x) fixed<<setprecision(x)
#define foru(a,b,c) for(ll a=b;a<=c;a++)

ll n,a[2000005],ans;

int main(){
    #ifndef ONLINE_JUDGE
        freopen("transportt.in" ,"r",stdin );
        freopen("transportt.out","w",stdout);
    #endif
    cin>>n;
    foru(i,1,n){
        cin>>a[i];
        a[i+n]=a[i];
    }
    foru(i,1,n-1){
        foru(j,i+1,n){
            ans=max(ans,a[i]+a[j]+min(abs(i-j),n-abs(i-j)));
        }
    }
    cout<<ans;
    return 0;
}