#include<bits/stdc++.h>
using namespace std;
typedef long long LL;
const int N=4e5+10;
LL w[N],s[N];
int q[N];
int main()
{
    int n;
    cin>>n;
    for(int i=1;i<=n;i++)
    {
        cin>>w[i];
        w[i+n]=w[i];
    }
    for(int i=1;i<=2*n;i++)
    {
        s[i]=s[i-1]+w[i];
    }
    LL ans=-1e18;
    int hh=0,tt=-1; //队头,队尾
    for(int i=1;i<=2*n;i++)
    {
        while(hh<=tt&&i-q[hh]+1>n+1) hh++; //当前区间元素过多
        ans=max(ans,s[i]-s[q[hh]]);//更新区间最值
        while(hh<=tt&&s[i]<s[q[tt]]) tt--; //去掉较大值
        q[++tt]=i;
    }
    cout<<ans;
    return 0;
}