#include <fstream>

using namespace std;
ifstream cin("oo.in");
ofstream cout("oo.out");
int main()
{
    int n,v[1001],i,k,minn=200000,stot=0,s=0,j;
    cin>>n;
    for(i=1;i<=n;i++){
        cin>>v[i];
        stot+=v[i];
    }
    for(i=1;i<n;i++){
            s=0;
            if(i==1){
                    s+=v[n];
                }
    else{
        for(int x=i-1;x>=1;x-=2){
            s+=v[x];
    }
    if(n%2==0){
        s+=v[i];
    }
    }
        for(j=i;j<=n;j+=2){
            s+=v[j]+v[j+1];
            if(s<minn){
                minn=s;
            }
        }
    }
    cout<<stot-minn;
    return 0;
}