import sys

sys.setrecursionlimit(10**7)
def I(): return int(sys.stdin.readline().rstrip())
def MI(): return map(int,sys.stdin.readline().rstrip().split())
def LI(): return list(map(int,sys.stdin.readline().rstrip().split()))
def LI2(): return list(map(int,sys.stdin.readline().rstrip()))
def S(): return sys.stdin.readline().rstrip()
def LS(): return list(sys.stdin.readline().rstrip().split())
def LS2(): return list(sys.stdin.readline().rstrip())


N = I()
L = LI()
K = I()

ok = 0
ng = max(L)+1
while ng-ok >= 10**-10:
    mid = (ok+ng)/2
    if sum(int(l/mid) for l in L) >= K:
        ok = mid
    else:
        ng = mid

print(ok)