#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; using namespace atcoder; typedef long long ll; #define rep(i, n) for (int i = 0; i < (int)(n); i++) #define repr(i, n) for (int i = (int)(n) - 1; i >= 0; i--) #define repk(i, k, n) for (int i = k; i < (int)(n); i++) #define all(v) v.begin(), v.end() #define mod1 1000000007 #define mod2 998244353 #define mod3 100000007 #define vi vector #define vs vector #define vc vector #define vl vector #define vb vector #define vvi vector> #define vvc vector> #define vvl vector> #define vvb vector> #define vvvi vector>> #define vvvl vector>> #define pii pair #define pil pair #define pli pair #define pll pair #define vpii vector> #define vpll vector> #define vvpii vector>> #define vvpll vector>> // using mint = modint998244353; template void debug(T e) { cerr << e << endl; } template void debug(vector &v) { rep(i, v.size()) { cerr << v[i] << " "; } cerr << endl; } template void debug(vector> &v) { rep(i, v.size()) { rep(j, v[i].size()) { cerr << v[i][j] << " "; } cerr << endl; } } template void debug(vector> &v) { rep(i, v.size()) { cerr << v[i].first << " " << v[i].second << endl; } } template void debug(set &st) { for (auto itr = st.begin(); itr != st.end(); itr++) { cerr << *itr << " "; } cerr << endl; } template void debug(multiset &ms) { for (auto itr = ms.begin(); itr != ms.end(); itr++) { cerr << *itr << " "; } cerr << endl; } template void debug(map &mp) { for (auto itr = mp.begin(); itr != mp.end(); itr++) { cerr << itr->first << " " << itr->second << endl; } } void debug_out() { cerr << endl; } template void debug_out(Head H, Tail... T) { cerr << H << " "; debug_out(T...); } using mint = modint1000000007; void debug_mint1(vector &vec) { for (int i = 0; i < vec.size(); i++) { cerr << vec[i].val() << " "; } cerr << endl; } void debug_mint2(vector> &vec) { for (int i = 0; i < vec.size(); i++) { for (int j = 0; j < vec[i].size(); j++) { cerr << vec[i][j].val() << " "; } cerr << endl; } } int main() { ll N; cin >> N; vector A(N); for (ll i = 0; i < N; i++) { cin >> A[i]; } // 左からの累積和と右からの累積和で vector suml(N + 2, 0); vector sumr(N + 2, 0); for (ll i = 0; i < N; i++) { suml[i + 1] = suml[i] + A[i]; } for (ll i = N - 1; i >= 0; i--) { sumr[i + 1] = sumr[i + 2] + A[i]; } ll INF = 1000000000000000023; ll nowmin = 0; ll nowmax = 0; vector minl(N + 2, INF); vector maxl(N + 2, -INF); for (ll i = 0; i < N; i++) { minl[i + 1] = min(minl[i], (suml[i + 1] - nowmax)); maxl[i + 1] = max(maxl[i], (suml[i + 1] - nowmin)); nowmin = min(nowmin, suml[i + 1]); nowmax = max(nowmax, suml[i + 1]); } nowmin = 0; nowmax = 0; vector minr(N + 2, INF); vector maxr(N + 2, -INF); for (ll i = N - 1; i >= 0; i--) { minr[i + 1] = min(minr[i + 2], (sumr[i + 1] - nowmax)); maxr[i + 1] = max(maxr[i + 2], (sumr[i + 1] - nowmin)); nowmin = min(nowmin, sumr[i + 1]); nowmax = max(nowmax, sumr[i + 1]); } // debug(minl); // debug(minr); ll ans = -INF; for (ll i = 1; i < N; i++) { ans = max(ans, minl[i] * minr[i + 1]); ans = max(ans, maxl[i] * maxr[i + 1]); } cout << ans << endl; }