N = gets.to_i
L = gets.split.take(N).map(&:to_i)
K = gets.to_i
M = 10**9
last = L.sum.quo(K).ceil * M
LL = L.map{|v| v * M }

ans = (0..last).bsearch{|_i|
  i = last - _i
  sum = LL.map{|l| (l / i).floor }.sum
  sum >= K
}
p (last - ans).fdiv(M)