def index(xs, x)
  left = 0
  right = xs.size
  100.times do
    i = (left + right) / 2
    if xs[i] < x
      left = i
    else
      right = i
    end
  end
  left
end

n = gets.to_i
ds = gets.chomp.split.map(&:to_i).sort
x, y = gets.chomp.split.map(&:to_i)
r = x.abs + y.abs

if r.zero?

  p 0

elsif ds.any? {|d| d == r}

  p 1

elsif r.even?

  d_max = ds.max
  if r <= d_max + d_max
    p 2
  else
    p -1
  end

else

  es = ds.select(&:even?).sort
  os = ds.select(&:odd?).sort
  e_max = es.max
  o_max = os.max

  if e_max == nil or o_max == nil
    p -1
    exit
  end

  os.each do |d|
    diff = (r - d).abs
    i = index(es, diff)
    (i-3..i+3).each do |j|
      d2 = es[j]
      next if d2 == nil
      if (d - d2).abs <= r and r <= d2 + d2
        p 2
        exit
      end
    end
  end

  es.each do |d|
    diff = (r - d).abs
    i = index(os, diff)
    (i-3..i+3).each do |j|
      d2 = os[j]
      next if d2 == nil
      if (d - d2).abs <= r and r <= d2 + d2
        p 2
        exit
      end
    end
  end

  p -1

end