#include <bits/stdc++.h>

using namespace std;
const int MAX_N = 1010;
int N;
vector<int> taste;
int dp[MAX_N][2];//0 not 1 use
int pre[MAX_N][2];
int main(){
  cin >> N;
  memset(pre, -1, sizeof(pre));
  taste.resize(N);
  for (int i = 0; i < N; i++){
    cin >> taste[i];
  }
  int res = 0;
  for (int i = 0; i < N; i++){
    dp[i + 1][1] = max(dp[i + 1][1], dp[i][0]);
    dp[i + 1][0] = max(dp[i + 1][0], max(dp[i][0], dp[i][1] + taste[i]));
    res = max(dp[i + 1][1], dp[i + 1][0]);
  }
  int pos = N;
  vector<int> ans;
  while (true){
    if (dp[pos][1] < dp[pos][0]){
      ans.push_back(pos);
      pos -= 2;
    }else{
      pos--;
    }
    if (pos < 1)break;
  }
  sort(ans.begin(), ans.end());
  cout << res << endl;

}