#ifdef LOCAL111 #else #define NDEBUG #endif #include const long long INF = 1e15; using namespace std; template ostream& operator<< (ostream& os, const pair& p) { cout << '(' << p.first << ' ' << p.second << ')'; return os; } #define endl '\n' #define ALL(a) (a).begin(),(a).end() #define SZ(a) int((a).size()) #define FOR(i,a,b) for(int i=(a);i<(b);++i) #define RFOR(i,a,b) for (int i=(b)-1;i>=(a);i--) #define REP(i,n) FOR(i,0,n) #define RREP(i,n) for (int i=(n)-1;i>=0;i--) #define RBP(i,a) for(auto& i : a) #ifdef LOCAL111 #define DEBUG(x) cout<<#x<<": "<<(x)< void dpite(T a, T b){ for(T ite = a; ite != b; ite++) cout << (ite == a ? "" : " ") << *ite; cout << endl;} #else #define DEBUG(x) true template void dpite(T a, T b){ return; } #endif #define F first #define S second #define SNP string::npos #define WRC(hoge) cout << "Case #" << (hoge)+1 << ": " #define rangej(a,b,c) ((a) <= (c) and (c) < (b)) #define rrangej(b,c) rangej(0,b,c) template void pite(T a, T b){ for(T ite = a; ite != b; ite++) cout << (ite == a ? "" : " ") << *ite; cout << endl;} template bool chmax(T& a, T b){if(a < b){a = b; return true;} return false;} template bool chmin(T& a, T b){if(a > b){a = b; return true;} return false;} typedef long long int LL; typedef unsigned long long ULL; typedef pair P; typedef pair LP; void ios_init(){ cout.setf(ios::fixed); cout.precision(12); #ifdef LOCAL111 return; #endif ios::sync_with_stdio(false); cin.tie(0); } int main() { ios_init(); int n; while(cin >> n) { vector bou(n); REP(i,n) cin >> bou[i]; LL k; cin >> k; double l = 0, r = INF; REP(hoge,100){ double m = (l+r)/2; LL num = 0; REP(i,n){ num += bou[i]/m; } // DEBUG(m); DEBUG(num); if(k > num){ r = m; }else{ l = m; } } cout << l << endl; } return 0; }