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

A.each_with_index do |a, i|
  pos[a] = i
end

checked = Hash.new(false)
ans = 0

A.sort.each do |a|
  idx = pos[a]
  next if checked[idx]

  checked[idx] = true
  checked[idx - 1] = true
  ans += 1
end

puts ans