#include <bits/stdc++.h>

using namespace std;
const int mxn = 100 * 1000 + 1;

int n, s;
int v1[ mxn ], v2[ mxn ];

int main()
{
    freopen("oo.in", "r", stdin);
    freopen("oo.out", "w", stdout);
    cin>> n;
    for (int i = 1; i <= n; i++)
        scanf("%d", &v1[ i ]);
    v1[ n + 1 ] = v1[ 1 ];
    for(int i = 1; i <= 3; i++){
        for(int j = i + 1; j <= n - 2 + i; j++){
            v2[ j ] = v1[ j ] + v1[ j - 1 ];
            for(int k = j - 3; k >= j - 5 && k > i; k--)
                v2[ j ] = max(v2[ j ], v1[ j ] + v1[ j - 1 ] + v2[ k ]);

           s = max(s, v2[ j ]);
        }
    }
    cout<< s;
}