rt

#include<iostream>
#include<cstring>
using namespace std;
const int Max=101,echou=-114514;
int sl1[Max][Max],sl2[Max][Max],ques[Max],ans[Max];
int search(int f,int b){
	for(int i=1;i<=b-f+1;i++){
		if(i%2==1){
			sl1[f][b]+=ques[f+i-1];
		}else{
			sl2[f][b]+=ques[f+i-1];
		}
	}
}


int main(){
	memset(sl1,0,sizeof(sl1));
	memset(sl2,0,sizeof(sl2));
	int n;
	cin>>n;
	for(int i=1;i<=n;i++){
	 	cin>>ques[i];
	 }
	for(int i=1;i<=n;i++){
	 	for(int j=i+1;j<=n;j++){
	 		search(i,j);
	 		sl1[j][i]=sl1[i][j];
	 		sl2[j][i]=sl2[i][j];
		}
	} 
	for(int i=1;i<=n;i++){
		int max=echou,p=1;
	 	for(int j=1;j<=n;j++){
	 		if(sl2[i][j]>max&&i!=j){
	 			p=j,max=sl2[i][j];
			}
		}
		ans[i]=sl1[i][p];
		//cout<<i<<" "<<p<<" "<<ans[i]<<endl;
	}
	int Fatal=echou; 
	for(int i=1;i<=n;i++){
		if(ans[i]>Fatal){
			Fatal=ans[i];
		}
	}
	cout<<Fatal<<endl;
}