use proconio::input;

fn main() {
  input! {
    n: usize,
    a: [i64; n],
  }
  if a.iter().all(|&ai| ai >= 0) {
    let ans = a.iter().min().unwrap();
    println!("{}", -ans);
  }

  let large = 2i64 << 48;
  let mut odd = -large;
  let mut even = 0;

  for &ai in a.iter() {
    odd = odd.max(even - ai);
    even = even.max(odd + ai);
  }

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