#include<iostream>
#include<algorithm>

using namespace std;

int N;
int arr[301] = { 0, };
int dp[301][3] = { 0, };

int main(){
    cin>> N;
    for(int i = 1; i<=N; i++){
      scanf("%d", &arr[i]);
    }
    if(N < 3){
      int ans = 0;
      for(int i = 1; i<=N; i++){
        ans += arr[i];
      }
      cout<< ans << endl;
      return 0;
    }
    dp[1][1] = arr[1];
    dp[2][1] = arr[2];
    dp[2][2] = dp[1][1] + arr[2];
    for(int i = 3; i<=N; i++){
      dp[i][1] = max(dp[i-2][1], dp[i-2][2]) + arr[i];
      dp[i][2] = dp[i-1][1] + arr[i];
    }
    int ans = 0;
    ans = max(dp[N][2] , dp[N][1]);
    cout<< ans <<endl;
}

#include <iostream>
#include <vector>
#include <algorithm>

std::vector<int> dp[2], st;

int main() {
	int n;
	std::cin >> n;
	for (int i = 0; i < n; i++) {
		int t;
		std::cin >> t;
		st.push_back(t);
	}

	dp[0].push_back(0);
	dp[0].push_back(st[1]);
	dp[1].push_back(st[0]);
	dp[1].push_back(st[0] + st[1]);
	
	for (int i = 2; i < n; i++) {
		dp[0].push_back(std::max(dp[0][i - 2], dp[1][i - 2]) + st[i]);
		dp[1].push_back(dp[0][i - 1] + st[i]);
	}

	std::cout << std::max(dp[0][n - 1], dp[1][n - 1]);
	return 0;
}