#include"bits/stdc++.h" //#include using namespace std; #define print(x) cout<= k)return 1; else { return 0; } } int main() { cin >> n; REP(i, n) { cin >> l[i]; } cin >> k; double lb =0, ub = 5; REP(i,100) { double mid = (lb + ub) / 2.0; if (check(mid)) { lb = mid; } else { ub = mid; } } print(ub); return 0; }