gets
a = gets.split.map(&:to_i)

count = 0
for i in 0..(a.size-3) do
  x, y, z = a[i], a[i+1], a[i+2]
  next if x == y || y == z || z == x
  next if x < y && y < z
  next if x > y && y > z
  count += 1
end

puts count