fn main() {
    let mut n = String::new();
    std::io::stdin().read_line(&mut n).ok();
    let n: usize = n.trim().parse().unwrap();
    let mut c = String::new();
    std::io::stdin().read_line(&mut c).ok();
    let c: Vec<isize> = c.trim().split_whitespace().map(|s| s.parse().unwrap()).collect();

    let summary = c.iter().sum::<isize>();
    let mut c = if summary < 0 { c.into_iter().map(|v| -v).collect::<Vec<_>>() } else { c };
    c.sort();
    c.reverse();
    let aval = c.iter().step_by(2).sum::<isize>();
    let bval = c.iter().skip(1).step_by(2).sum::<isize>();
    println!("{}", aval.abs() - bval.abs());
}