#include <bits/stdc++.h> using namespace std; #define print(l) for(auto i:l) cout<<i<<" ";cout<<endl; #define input(t,l,n) vector<t>l(n);for(int i = 0;i<n;i++)cin>>l[i]; #define int long long #define pb push_back #define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update> #define all(l) l.begin(),l.end() #define pii pair<int,int> #define fi first #define se second const int M = 1e9+7; const int inf = 1e18; int bp(int x, int y, int p){ int res = 1; x = x % p; while (y > 0) { if (y & 1) res = (res * x) % p; y = y >> 1; x = (x * x) % p; } return res; } int MI(int n, int p){ return bp(n, p - 2, p); } int mul(int x,int y, int p){ return x * 1ull * y % p; } int di(int x,int y, int p){ return mul(x, MI(y, p), p); } int n , m , k , q; void solve(int testcase_number){ cin>>n; input(int,a,n); int dp[n+1][n+1]; for(int i =0 ;i<=n;i++){ for(int j = 0;j<=n;j++){ dp[i][j] = 0; } } for(int i = 0;i<n;i++){ dp[i][i] = a[i]; } for(int sz = 2;sz<=n;sz++){ for(int l = 0;l+sz-1<n;l++){ int r = l+sz-1; if(l+1<n) dp[l][r] = (dp[l+1][r]+a[l])/2; if(r-1>=0) dp[l][r] = max(dp[l][r],(dp[l][r-1]+a[r])/2); } } cout<<dp[0][n-1]<<endl; } signed main(){ ios::sync_with_stdio(0);//DO NOT USE IN INTERACTIVE cin.tie(0), cout.tie(0); cout << fixed<<setprecision(9); int t = 1; // cin>>t; for(int i = 1;i<=t;i++){ solve(i); } }