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

counter = Hash.new(0)
left = 0
right = 0
counter[A[0]] += 1
ans = 1

while left <= right
  if right == N - 1
    counter[A[left]] -= 1
    left += 1
  elsif counter[A[right]] >= 2
    counter[A[left]] -= 1
    left += 1
  else
    right += 1
    counter[A[right]] += 1
  end

  if counter[A[right]] <= 1
    len = right - left + 1
    ans = len if ans < len
  end
end

puts ans