#include #include using namespace std; long long N,K; double m,M,mid,L[200000]; int check(double mid){ int count=0; for(int i=0;i=K) return 1; else return 0; } int main(){ cin >> N; for(int i=0;i> L[i]; cin >> K; m = 0; M=10000000000; for(int i=0;i<100;i++){ mid = (m+M)/2; if(check(mid)) m = mid; else M = mid; } printf("%0.10lf\n",m); return 0; }