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

int n;
int tastes[1002];
int dp[1002][2];

int main()
{
    cin >> n;
    for (int i = 0; i < n; i++)
        cin >> tastes[i];

    memset(dp, 0, sizeof(dp));

    for (int i = 0; i < n; i++)
    {
        dp[i + 1][0] += max(dp[i][0], dp[i][1]);
        dp[i + 1][1] += dp[i][0] + tastes[i];
    }

    cout << max(dp[n][0], dp[n][1]) << endl;
}