//#pragma GCC target("avx2") //#pragma GCC optimize("O3") //#pragma GCC optimize("unroll-loops") #include using namespace std; using ll = long long; using pii = pair; using pll = pair; using pli = pair; #define AMARI 998244353 //#define AMARI 1000000007 #define el '\n' #define El '\n' #define YESNO(x) ((x) ? "Yes" : "No") #define YES YESNO(true) #define NO YESNO(false) #define REV_PRIORITY_QUEUE(tp) priority_queue,greater> #define EXIT_ANS(x) {cout << (x) << '\n'; return;} template void inline SORT(vector &v){sort(v.begin(),v.end()); return;} template void inline VEC_UNIQ(vector &v){sort(v.begin(),v.end()); v.erase(unique(v.begin(),v.end()),v.end()); return;} template T inline MAX(vector &v){return *max_element(v.begin(),v.end());} template T inline MIN(vector &v){return *min_element(v.begin(),v.end());} template T inline SUM(vector &v){T ans = 0; for(int i = 0; i < (int)v.size(); i++)ans += v[i]; return ans;} void inline TEST(void){cerr << "TEST" << endl; return;} vector> inline get_graph(int n,int m = -1,bool direct = false){ if(m == -1)m = n - 1; vector> g(n); while(m--){ int u,v; cin >> u >> v; u--; v--; g[u].push_back(v); if(!direct)g[v].push_back(u); } return g; } vector make_max(vector const& a){ int n = (int)a.size(); vector ans(n); ll mn = 0LL; ll temp = 0LL; for(int i = 0; i < n; i++){ temp += a[i]; ans[i] = temp - mn; if(i)ans[i] = max(ans[i],ans[i - 1]); ans[i] = max(ans[i],a[i]); mn = min(mn,temp); } return ans; } ll func(vector a){ vector temp = make_max(a); reverse(a.begin(),a.end()); vector temp2 = make_max(a); reverse(temp2.begin(),temp2.end()); ll ans = LLONG_MIN / 2LL; int n = (int)a.size(); for(int i = 0; i < n - 1; i++){ ans = max(ans,temp[i] * temp2[i + 1]); } return ans; } #define MULTI_TEST_CASE false void solve(void){ //問題を見たらまず「この問題設定から言えること」をいっぱい言う //よりシンプルな問題に言い換えられたら、言い換えた先の問題を自然言語ではっきりと書く //複数の解法のアイデアを思いついた時は全部メモしておく //g++ -D_GLIBCXX_DEBUG -Wall -O2 f.cpp -o o int n; cin >> n; vector a(n); for(int i = 0; i < n; i++){ cin >> a[i]; } ll ans = func(a); for(int i =0 ; i < n; i++){ a[i] *= -1; } ans = max(ans,func(a)); cout << ans << el; return; } void calc(void){ return; } signed main(void){ cin.tie(nullptr); ios::sync_with_stdio(false); calc(); int t = 1; if(MULTI_TEST_CASE)cin >> t; while(t--){ solve(); } return 0; }