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();

  let result = a
    .windows(3)
    .filter(|a| a[0] != a[1] && a[1] != a[2] && a[2] != a[0])
    .filter(|a| {
      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();

  println!("{}", result);
}