mod io {
    #[macro_export]
    macro_rules! scan {
        ($r:expr, [$t:tt; $n:expr]) => (
            (0..$n).map(|_| scan!($r, $t)).collect::<Vec<_>>()
        );
        ($r:expr, ($($t:tt),*)) => (($(scan!($r, $t)),*));
        ($r:expr, Usize1) => (scan!($r, usize) - 1);
        ($r:expr, String) => (String::from_utf8(scan!($r, Bytes)).unwrap());
        ($r:expr, Bytes) => (io::scan($r));
        ($r:expr, Chars) => (scan!($r, String).chars().collect::<Vec<_>>());
        ($r:expr, $t:ty) => (scan!($r, String).parse::<$t>().unwrap());
    }

    use std::io::{BufRead, ErrorKind};

    pub fn scan<R: BufRead>(r: &mut R) -> Vec<u8> {
        let mut buf = Vec::new();
        loop {
            let (done, used) = {
                let available = match r.fill_buf() {
                    Ok(n) => n,
                    Err(ref e) if e.kind() == ErrorKind::Interrupted => continue,
                    Err(e) => panic!(e), 
                };
                match available.iter().position(u8::is_ascii_whitespace) {
                    Some(i) => {
                        buf.extend_from_slice(&available[..i]);
                        (buf.len() > 0, i + 1)
                    }
                    None => {
                        buf.extend_from_slice(available);
                        (false, available.len())
                    }
                }
            };
            r.consume(used);
            if done || used == 0 {
                return buf;
            }
        }
    }
}

use std::io::{BufRead, Write};

fn run<R: BufRead, W: Write>(reader: &mut R, writer: &mut W) {
    let n = scan!(reader, usize);
    let mut c = scan!(reader, [i64; n]);

    if c.iter().sum::<i64>() > 0 {
        c.sort_by(|a, b| b.cmp(a));
    } else {
        c.sort();
    }

    let mut sum = [0, 0];
    for (i, c) in c.iter().enumerate() {
        sum[i & 1] += c;
    }
    
    let ans = sum[0].abs() - sum[1].abs();
    writeln!(writer, "{}", ans).ok();
}

fn main() {
    let (stdin, stdout) = (std::io::stdin(), std::io::stdout());
    let mut reader = std::io::BufReader::new(stdin.lock());
    let mut writer = std::io::BufWriter::new(stdout.lock());
    run(&mut reader, &mut writer);
}