n = read_line.to_i
s, t = read_line.split.map(&.to_i)
a = read_line.split.map(&.to_i) + [s, t]
hash = a.zip(0..).to_h
que = Deque{n}
dist = [nil.as(Int32?)] * (n + 2)
dist[n] = -1
while i = que.shift?
  d = dist[i].not_nil!
  puts(d) + exit if i == n + 1
	a.each_with_index do |x, j|
		if (a[i] ^ x).popcount == 1
			dist[j] = d + 1
			que << j
		end
	end
end
puts -1