N = gets.to_i
A = gets.split.map(&:to_i)

def dfs(nums, mb)
  return nums.max if mb == 0
  return 0 if nums.empty?

  base = 1 << mb
  cand = nums.group_by { |x| x[mb] }
  cand.default = []

  v = 0

  if cand[0].size > 0 && cand[1].size > 0
    v = [
      dfs(cand[0].map { |x| x ^ base }, mb - 1),
      dfs(cand[1], mb - 1)
    ].max
  elsif cand[0].size > 0
    v = dfs(cand[0], mb - 1)
  elsif cand[1].size > 0
    v = dfs(cand[1].map { |x| x ^ base }, mb - 1)
  end

  v
end

mb = A.map(&:bit_length).max
puts dfs(A, mb - 1)