#include <cstdio>
using namespace std;
int v[100005];
int d[100005];
bool a[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];
    if(d[1]<v[1]+v[n])d[1]=v[1]+v[n];
    a[1]=1;
    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,a[i]=a[i+1]=1;
    }
    d[n]=d[n-1];
    printf("%d\n",d[n]);
    return 0;
}