#!/usr/bin/env ruby

INF = 10**18 + 1;

n, m = gets.split.map(&:to_i)
as = gets.split.map(&:to_i)
ks = gets.split.map(&:to_i)

lim = as[-1]
dp = []
loop do
  dp = (0 .. lim).map{ INF }
  dp[0] = 0
  as.each do |a|
    a.upto(lim) do |x|
      if dp[x] > dp[x - a] + 1
        dp[x] = dp[x - a] + 1
      end
    end
  end
  if lim >= as[-1] then
    ok = true
    lim.downto(lim - as[-1]) do |x|
      ok &&= (dp[x] == INF || dp[x] == dp[x - as[-1]] + 1)
    end
    if ok then
      break
    end
  end
  lim <<= 1
end

STDERR.puts lim

target = -m
n.times do |i|
  target += as[i] * ks[i];
end

if target < 0
  ans = INF
elsif target < lim
  ans = dp[target]
else
  greed = ((target - lim) + as[-1] - 1) / as[-1]
  ans = greed + dp[target - as[-1] * greed]
end

if ans >= INF
  p -1
else
  p ans
end