n = gets.to_i
count = 0
a_list = gets.split.map(&:to_i)
n.downto(2) do |i|
  next unless a_list.index(i) < a_list.index(i - 1)
  a_list.delete(i - 1)
  a_list.unshift(i - 1)
  count += 1
end
puts count