N = int(input())
L = list(map(int,input().split()))
K = int(input())

left = 0
right = 10**10 + 1

ans = 0

def search(mid,K,L):
    count = 0
    for i in range(N):
        if(L[i] >= mid):
            count += L[i] // mid
    
    if(count >= K):
        return True        


for i in range(100):
    mid = (left + right) / 2
    if(search(mid,K,L)):
        left = mid
        ans = max(ans,mid)
    else:
        right = mid

print(ans)