fn read<T: std::str::FromStr>() -> T {
  let mut s = String::new();
  std::io::stdin().read_line(&mut s).ok();
  s.trim().parse().ok().unwrap()
}

fn main() {
  let n: usize = read();
  println!("{}", no111(n));
}

fn no111(n:usize) -> usize {
  if n % 2 == 0 {
    0
  } else {
    let a = (n + 1) / 2;
    let b = n - a;
    patterns(a) + patterns(b)
  }
}

fn patterns(n:usize) -> usize {
  let mut result = 0;
  for i in (1..=n).rev() {
    result = result + (i-1);
  }
  result
}