n = gets.to_i
@cheby = gets.strip.split(' ').map(&:to_i)
#p @cheby
@goal = gets.strip.split(' ').map(&:to_i)
#p @goal
x, y = 0, 0


points_x = [0]
count_x = 0
100.times do
	next_points_x = []
	count_x += 1
	points_x.each do |point_x|
		@cheby.each do |d|
			next_points_x << point_x - d
			next_points_x << point_x + d
		end
	end
	if next_points_x.include?(@goal[0])
		#p count_x
		break
	end
	#p next_points
	points_x = next_points_x.uniq
end
#p points_x

points_y = [0]
count_y = 0
100.times do
	next_points_y = []
	count_y += 1
	points_y.each do |point_y|
		@cheby.each do |d|
			next_points_y << point_y - d
			next_points_y << point_y + d
		end
	end
	if next_points_y.include?(@goal[1])
		#p count_y
		break
	end
	#p next_points
	points_y = next_points_y.uniq
end
#p points_y
p [count_x, count_y].max