n = gets.to_i
d = gets.split.map(&:to_i)
x, y = gets.split.map(&:to_i)
if x == 0 && y == 0
    p 0
elsif d.include?(x.abs + y.abs)
    p 1
elsif d.max * 2 >= (x.abs + y.abs)
    p 2
else
    p -1
end