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 mut c: Vec<isize> = c.trim().split_whitespace().map(|s| s.parse().unwrap()).collect();

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