Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();
    int arr[] = new int[n];
    for (int i = 0; i < n; i++) {
        arr[i] = sc.nextInt();
    }
    int sum = 0;
    for (int i = 0; i < n; i++)
        sum = sum + arr[i];

    int min[] = new int[n];
    min[0] = arr[0];
    min[1] = arr[1];
    min[2] = arr[2];
    for (int i = 3; i < n; i++)
        min[i] = arr[i] + minimum(min[i - 1], min[i - 2], min[i - 3]);

    int val = sum - minimum(min[n - 1], min[n - 2], min[n - 3]);
    System.out.println(val);