#include <iostream>
#include <algorithm>
using namespace std;

int dp[1010][2];
int deli[1010];
int main() {
	int n;
	cin >> n;
	for (int i = 1; i <= n; i++) {
		cin >> deli[i];
	}
	for (int i = 0; i < n; i++) {
		dp[i][0] = dp[i][1] = 0;
}
	dp[0][0] = 0;
	for (int i = 1; i <= n; i++) {
		dp[i][1] = dp[i - 1][0] + deli[i];
		dp[i][0] = max(dp[i - 1][1], dp[i - 1][0]);
	}
	cout << max(dp[n][1], dp[n][0]);
	return 0;
}