#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #define rep(i, n) for (int i = 0; i < (int)(n); ++i) //#define cerr if(false) cerr #ifdef DEBUG #define show(...) cerr << #__VA_ARGS__ << " = ", debug(__VA_ARGS__); #else #define show(...) 42 #endif using namespace std; using ll = long long; using pii = pair; template ostream& operator<<(ostream& os, pair a) { os << '(' << a.first << ',' << a.second << ')'; return os; } template ostream& operator<<(ostream& os, vector v) { for (auto x : v) os << x << ' '; return os; } void debug() { cerr << '\n'; } template void debug(H a, T... b) { cerr << a; if (sizeof...(b)) cerr << ", "; debug(b...); } int Find_median(vectora){ assert(a.size()<=5); sort(a.begin(),a.end()); return a[a.size()/2]; } //T(n) = T(n/5) + T() + O(n) int kth_smallest(const vector&a, int l, int r, int k){ if(k <= 0 or r - l < k)return INT_MAX; vectormed; for(int i = l; i < r;){ vectortemp; for(int j = 0; j < 5; j++){ if(i < r) temp.push_back(a[i++]); } med.push_back(Find_median(temp)); } int medofmed = (med.size() == 1) ? med[0] : kth_smallest(med, 0, (int) med.size(), (int) med.size() / 2); vector b,c,d; for (int i = l; i < r; i++){ if(a[i] < medofmed){ b.push_back(a[i]); }else if(a[i] == medofmed){ c.push_back(a[i]); }else{ d.push_back(a[i]); } } if(b.size() >= k){ return kth_smallest(b, 0, (int) b.size(), k); }else if(b.size() + c.size() >= k){ return medofmed; }else{ return kth_smallest(d, 0, (int) d.size(), k - (int) b.size() - (int) c.size()); } return INT_MAX; } int main(){ cin.tie(nullptr); ios::sync_with_stdio(false); int n; cin >> n; const int offset = 1e9; vectora(n); rep(i,n)cin >> a[i]; rep(i,n)a[i] += offset; ll ans = -(1LL<<60); for(int k = 1; k <= n; k++){ ll sum = 0; const int pos = (k - 1)/ 2 + 1; show(pos); vector dp[2]; for(int i = 0; i + k <= n; i+= k){ dp[0].push_back((ll)k * (kth_smallest(a,i, i + k, pos) - offset)); } for(int i = n; i - k >= 0; i-= k){ dp[1].push_back((ll)k * (kth_smallest(a,i - k, i, pos) - offset)); } show(dp[0],dp[1]); const int sz = (int) dp[0].size(); rep(i,2){ sum = max(sum,dp[i][0]); rep(j,sz-1){ dp[i][j+1] += dp[i][j]; sum = max(sum, dp[i][j+1]); } } vector rui(sz); rep(i,sz){ if(i==0)rui[i] = dp[0][0]; else rui[i] = max(rui[i-1], dp[0][i]); } rep(i,sz-1){ sum = max(sum, rui[i] + dp[1][sz - 2 -i]); } show(k, sz, sum); ans = max(ans, sum); } cout << ans << endl; }