use proconio::input;

fn main() {
  input! {
    n: usize,
    a: [i64; n],
  }
  if n <= 1 {
    println!("{}", -a[0]);
    return;
  }

  let mut odd = (-a[0]).max(-a[1]);
  let mut even = -a[0] + a[1];

  for &ai in a[2..].iter() {
    let odd_next = odd.max(even - ai).max(-ai);
    let even_next = even.max(odd + ai);
    odd = odd_next;
    even = even_next;
  }

  println!("{}", odd.max(even));
}