#define _USE_MATH_DEFINES #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include typedef long long int ll; //#include using namespace std; ll gcd(ll a, ll b) { if (a < b)swap(a, b); if (b == 0)return a; return gcd(b, a % b); } int lcm(int a, int b) { return a * b / gcd(a, b); } int main() { int Q; Q = 1; //cin >> Q; while (Q--) { int n; cin >> n; vectorp(n); for (int i = 0; i < n; i++)cin >> p[i]; vectort(n + 4); for (int i = 0; i < n; i++) { t[i + 1] = max(t[i], t[i + 1]); t[i + 2] = max(t[i + 2], t[i] + p[i]); } ll ans = 0; for (int i = 0; i < n+2; i++) { ans = max(ans, t[i]); } cout << ans; } return 0; }