#include using namespace std; typedef long long ll; #define REP(i,n) for(int i=0; i #define VLL vector #define VVI vector> #define VVLL vector> #define VC vector #define VS vector #define VVC vector> #define fore(i,a) for(auto &i:a) typedef pair P; template bool chmax(T &a, T b) { if (a < b) { a = b; return true; } return false; } template bool chmin(T &a, T b) { if (a > b) { a = b; return true; } return false; } const int INF = 1 << 30; const ll INFL = 1LL<<60; const ll mod = 1000000007; int main() { int n; cin >> n; VI v(n); REP(i, n)cin >> v[i]; VI dp(n + 10); dp[0] = 0; dp[1] = v[0]; REP(i, n - 1) { dp[i + 2] = max(dp[i + 1], dp[i] + v[i + 1]); } cout << dp[n] << endl; return 0; }