#pragma GCC optimize("O3") #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; using ll = long long; using P = pair; using T = tuple; template inline T chmax(T &a, const T b) {return a = (a < b) ? b : a;} template inline T chmin(T &a, const T b) {return a = (a > b) ? b : a;} constexpr int MOD = 1e9 + 7; constexpr int inf = 1e9; constexpr long long INF = 1e18; constexpr double pi = acos(-1); constexpr double EPS = 1e-10; int dx[] = {1, 0, -1, 0}; int dy[] = {0, 1, 0, -1}; int main(){ cin.tie(0); ios::sync_with_stdio(false); int n; cin>>n; double a = 4; for(int i=0; i