#include<iostream>
#include<string>
#include<algorithm>
#include<iomanip>
using namespace std;
#define int long long
#define rep(i,n) for(int i = 0; i < n; i++)
#define INF (long long)(1e18)
#define MOD (int)(1e9+7)
#define MAX_N (int)(2*1e5+10)
#define MAX_V 10
#define MAX_M 101
#define yn(f) (f?"Yes":"No")
#define YN(f) (f?"YES":"NO")
#define pro "はいプロ　世界一○○が上手　○○界のtourist　○○時代の終焉を告げる者　実質○○　○○するために生まれてきた男"

int L[MAX_N];
signed main(){
	cout<<fixed<<setprecision(10);
	int N, K, sum = 0;
	double high, low, mid;
	cin>>N;
	rep(i,N){
		cin>>L[i];
		sum += L[i];
	}
	cin>>K;
	sort(L,L+N);
	low = L[0]/K; high = (double)sum/K+1;
	
	for(int i = 0; i <= 100; i++){
		mid = (low + high)/2;
		int count = 0;
		for(int i = 0; i < N; i++){
			count += L[i]/mid;
		}
		if(count >= K) low = mid;
		else if(count < K) high = mid;
		// cout<<count<<" "<<mid<<endl;
		// cin>>count;
	}
	cout<<mid<<endl;
	return 0;
}