#include <bits/stdc++.h>
using namespace std;
const long double PI = 3.1415926535897923846;
const long long int MOD = 1000000007;
const long long int N = 998244353;
long long int power(long long int x, long long int n) {
  long long int res = 1;
  while (n > 0) {
    if (n & 1) res = res * x % MOD;
    x = x * x % MOD;
    n >>= 1;
  }
  return res;
}
long long int modinverse(long long int a) { return power(a, MOD - 2); }
void solve() {
  long long int n;
  cin >> n;
  vector<long long int> a(n);
  for (long long int i = 0; i < n; i++) {
    cin >> a[i];
  }
  vector<long long int> pref = a, suf = a;
  for (long long int i = 0; i + 2 < n; i++) pref[i + 2] += pref[i];
  for (long long int i = n - 1; i >= 2; i--) suf[i - 2] += suf[i];
  long long int ans = pref[n - 1];
  for (long long int i = 0; i < n - 1; i++)
    ans = max(ans, pref[i] + suf[i + 1]);
  cout << ans << endl;
}
int main() {
  long long int test = 1;
  while (test--) {
    solve();
  }
}
