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

def calc_bou(N, L, K):
    low = 0
    high = max(L)

    for _ in range(60):
        mid = (low + high) / 2
        cnt = 0
        for i in L:
            cnt += i // mid
        if cnt < K:
            high = mid
        else:
            low = mid
    
    return low

print(calc_bou(N, L, K))