#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define endl "\n"
ll segtree[4000020];
ll pf[1000005];
void build(ll id,ll l,ll r)
{
if(l==r)
{
segtree[id]=pf[l];
return;
}
ll mid=(l+r)/2;
build(id*2,l,mid);
build(id*2+1,mid+1,r);
segtree[id]=max(segtree[id*2],segtree[id*2+1]);
}
ll get(ll id,ll l,ll r,ll u,ll v)
{
if(r<u||l>v)
{
return 0;
}
if(u<=l&&r<=v)
{
return segtree[id];
}
ll mid=(l+r)/2;
return max(get(id*2,l,mid,u,v),get(id*2+1,mid+1,r,u,v));
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
ll t=1;
//cin>>t;
while(t--)
{
ll n;
cin>>n;
ll a[2*n+1],i,tong=0;
a[0]=0;
for(i=1;i<=n;i++)
{
cin>>a[i];
tong+=a[i];
a[i+n]=a[i];
}
ll len=n/2,tong1=0;
for(i=1;i<=2*n;i++)
{
tong1+=a[i];
if(i<len)
{
continue;
}
if(i==len)
{
pf[i]=tong1;
continue;
}
pf[i]=pf[i-1]+a[i]-a[i-len];
//cout<<pf[i]<<endl;
}
build(1,1,2*n);
ll val=1e18;
for(i=1;i<=n;i++)
{
//cout<<get(1,1,2*n,i+1,i+n-1)<<endl;
val=min(val,get(1,1,2*n,i+len,i+n-1));
}
cout<<tong-val<<endl;
}
#ifndef ONLINE_JUDGE
cerr << "Time elapsed: " << 1.0 * clock() / CLOCKS_PER_SEC << " s.\n";
#endif
return 0;
}
// Author: tryharderforioi100
