#include<bits/stdc++.h>
using namespace std;
long long n,a[51],a1,a2;
int main(){
	cin>>n;
	for(int i=1;i<=n;i++){
		cin>>a[i];
	}
	for(int i=1;i<=n;i+=2)
	{
		a1+=a[i];
	}
	for(int i=2;i<=n;i+=2){
		a2+=a[i];
	}
	cout<<max(a1,a2);
} 
/**************************************************************
	Problem: 1653
	User: wuyunfeng
	Language: C++
	Result: Wrong Answer
****************************************************************/