use std::io;

fn main() {
  let mut buf = String::new();
  io::stdin().read_line(&mut buf).ok();

  let mut buf = String::new();
  io::stdin().read_line(&mut buf).ok();
  let a: Vec<u16> = buf
    .trim()
    .split_whitespace()
    .map(|e| e.parse().ok().unwrap())
    .collect();

  println!(
    "{}",
    a.windows(3)
      .filter(|a| (a[0] != a[1] && a[1] != a[2] && a[2] != a[0])
        && (a[1] > if a[0] > a[2] { a[0] } else { a[2] }
          || a[1] < if a[0] > a[2] { a[2] } else { a[0] })).count()
  );
}