#include <cstdio>
using namespace std;
int v[100005];
int d[100005];
int d1[100005];
int main()
{
    freopen("oo.in","r",stdin);
    freopen("oo.out","w",stdout);
    int n ,i;
    scanf("%d",&n);
    for(i=1;i<=n;i++)scanf("%d",&v[i]);
    int x=n-1;
    d[1]=v[1]+v[2];
    for(i=2;i<n;i++)
    {
        int v1=d[i-3]+v[i]+v[i+1];
        int v2 =d[i-1];
        if(v1<v2)d[i]=v2;
        else
            d[i]=v1;
    }
    d[n]=d[n-1];

    d1[1]=v[1]+v[n];
    //a[1]=1;
    for(i=2;i<n-1;i++)
    {
        int v1=d1[i-3]+v[i]+v[i+1];
        int v2 =d1[i-1];
        if(v1<v2)d1[i]=v2;
        else
            d1[i]=v1;
    }
    d1[n]=d1[n-2];
    int val=d1[n];
    if(val<d[n])val=d[n];
    printf("%d\n",val);
    return 0;
}