// BOI 2015 - Hacker
// Lúcio Cardoso
#include <bits/stdc++.h>
using namespace std;
const int maxn = 5e5+10;
const int inf = 1e9+10;
int n;
int v[2*maxn];
int tree[4*maxn], lazy[4*maxn];
void init(void)
{
for (int i = 0; i < 4*maxn; i++)
tree[i] = lazy[i] = inf;
}
void flush(int node, int l, int r)
{
if (lazy[node] == inf) return;
tree[node] = min(tree[node], lazy[node]);
if (l != r)
{
lazy[2*node] = min(lazy[2*node], lazy[node]);
lazy[2*node+1] = min(lazy[2*node+1], lazy[node]);
}
lazy[node] = inf;
}
void upd(int node, int l, int r, int a, int b, int v)
{
flush(node, l, r);
if (l > b || r < a) return;
if (l >= a && r <= b)
{
lazy[node] = v;
flush(node, l, r);
return;
}
int mid = (l+r)>>1;
upd(2*node, l, mid, a, b, v); upd(2*node+1, mid+1, r, a, b, v);
tree[node] = min(tree[2*node], tree[2*node+1]);
}
int query(int node, int l, int r, int pos)
{
flush(node, l, r);
if (l == r) return tree[node];
int mid = (l+r)>>1;
if (pos <= mid) return query(2*node, l, mid, pos);
return query(2*node+1, mid+1, r, pos);
}
int main(void)
{
init();
cin >> n;
int m = (n+1)/2;
for (int i = 1; i <= n; i++)
{
cin >> v[i];
v[n+i] = v[i];
}
int soma = 0;
for (int i = 1; i <= m; i++)
soma += v[i];
upd(1, 1, n, 1, m, soma);
int ans = 0;
for (int i = m + 1; i-m+1 <= n; i++)
{
soma -= v[i-m];
soma += v[i];
if (i <= n) upd(1, 1, n, i-m+1, i, soma);
else
{
upd(1, 1, n, i-m+1, n, soma);
upd(1, 1, n, 1, i-n, soma);
}
}
for (int i = 1; i <= n; i++)
ans = max(ans, query(1, 1, n, i));
cout << ans << "\n";
}
