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

    let mut _n = _n.trim().parse::<usize>().unwrap();

    let mut input = String::new();
    std::io::stdin().read_line(&mut input).ok();

    let a_vec = input
        .trim()
        .split_whitespace()
        .map(|x| x.parse::<usize>().unwrap())
        .collect::<Vec<_>>();

    println!(
        "{}",
        a_vec
            .windows(3)
            .filter(|x| (x[0] != x[1] && x[1] != x[2] && x[2] != x[0]))
            .filter(|x| (x.iter().max().unwrap() == &x[1]) || (x.iter().min().unwrap() == &x[1]))
            .count()
    );
}