#include<bits/stdc++.h>
using namespace std;
int main(){
  int N,i,p=0,q=0,tmp=0;
  cin >> N;
  while(N--){
    cin >> i;
    tmp = p;
    p = q + i;
    q = tmp>q?tmp:q;
  }

  cout << (p>q ? p : q) << endl;
  return 0;
}