// -*- coding:utf-8-unix -*-

#![allow(dead_code)]
#![allow(unused_imports)]
use std::collections::*;
use std::convert::*;
use std::convert::{From, Into};
use std::fmt::Debug;
use std::fs::File;
use std::io::prelude::*;
use std::io::*;
use std::marker::Copy;
use std::mem::*;
use std::ops::Bound::*;
use std::ops::{Add, Mul, Neg, Sub};
use std::str;
use std::vec;
use std::{cmp, process::Output};
use std::{cmp::Ordering, env::consts::DLL_PREFIX};
use std::{cmp::Ordering::*, f32::consts::PI};

const INF: i64 = 1223372036854775807;
const FINF: f64 = 122337203685.0;
const LINF: i64 = 2147483647;
const UINF: usize = INF as usize;
const MEM_SIZE: usize = 202020;
// const MOD: i64 = 1000000007;
const MOD: i64 = 998244353;
const UMOD: usize = MOD as usize;
use std::cmp::*;
use std::collections::*;
use std::io::stdin;
use std::io::stdout;
use std::io::Write;

// use str::Chars;
#[allow(dead_code)]
fn read<T: std::str::FromStr>() -> T {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    s.trim().parse().ok().unwrap()
}

#[allow(dead_code)]
fn readi() -> (i64) {
    let mut str = String::new();
    let _ = stdin().read_line(&mut str).unwrap();
    let mut iter = str.split_whitespace();
    iter.next().unwrap().parse::<i64>().unwrap()
}

#[allow(dead_code)]
fn read_vec<T: std::str::FromStr>() -> Vec<T> {
    read::<String>()
        .split_whitespace()
        .map(|e| e.parse().ok().unwrap())
        .collect()
}
#[allow(dead_code)]
fn read_vec2<T: std::str::FromStr>(n: u32) -> Vec<Vec<T>> {
    (0..n).map(|_| read_vec()).collect()
}

#[allow(dead_code)]
fn readii() -> (i64, i64) {
    let mut str = String::new();
    let _ = stdin().read_line(&mut str).unwrap();
    let mut iter = str.split_whitespace();
    (
        iter.next().unwrap().parse::<i64>().unwrap(),
        iter.next().unwrap().parse::<i64>().unwrap(),
    )
}

fn readff() -> (f64, f64) {
    let mut str = String::new();
    let _ = stdin().read_line(&mut str).unwrap();
    let mut iter = str.split_whitespace();
    (
        iter.next().unwrap().parse::<f64>().unwrap(),
        iter.next().unwrap().parse::<f64>().unwrap(),
    )
}

#[allow(dead_code)]
fn readiii() -> (i64, i64, i64) {
    let mut str = String::new();
    let _ = stdin().read_line(&mut str).unwrap();
    let mut iter = str.split_whitespace();
    (
        iter.next().unwrap().parse::<i64>().unwrap(),
        iter.next().unwrap().parse::<i64>().unwrap(),
        iter.next().unwrap().parse::<i64>().unwrap(),
    )
}
#[allow(dead_code)]
fn readuu() -> (usize, usize) {
    let mut str = String::new();
    let _ = stdin().read_line(&mut str).unwrap();
    let mut iter = str.split_whitespace();
    (
        iter.next().unwrap().parse::<usize>().unwrap(),
        iter.next().unwrap().parse::<usize>().unwrap(),
    )
}

fn readcc() -> (char, char) {
    let mut str = String::new();
    let _ = stdin().read_line(&mut str).unwrap();
    let mut iter = str.split_whitespace();
    (
        iter.next().unwrap().parse::<char>().unwrap(),
        iter.next().unwrap().parse::<char>().unwrap(),
    )
}

#[allow(dead_code)]
fn readuuu() -> (usize, usize, usize) {
    let mut str = String::new();
    let _ = stdin().read_line(&mut str).unwrap();
    let mut iter = str.split_whitespace();
    (
        iter.next().unwrap().parse::<usize>().unwrap(),
        iter.next().unwrap().parse::<usize>().unwrap(),
        iter.next().unwrap().parse::<usize>().unwrap(),
    )
}

#[allow(dead_code)]
fn readuuuu() -> (usize, usize, usize, usize) {
    let mut str = String::new();
    let _ = stdin().read_line(&mut str).unwrap();
    let mut iter = str.split_whitespace();
    (
        iter.next().unwrap().parse::<usize>().unwrap(),
        iter.next().unwrap().parse::<usize>().unwrap(),
        iter.next().unwrap().parse::<usize>().unwrap(),
        iter.next().unwrap().parse::<usize>().unwrap(),
    )
}

fn readiiii() -> (i64, i64, i64, i64) {
    let mut str = String::new();
    let _ = stdin().read_line(&mut str).unwrap();
    let mut iter = str.split_whitespace();
    (
        iter.next().unwrap().parse::<i64>().unwrap(),
        iter.next().unwrap().parse::<i64>().unwrap(),
        iter.next().unwrap().parse::<i64>().unwrap(),
        iter.next().unwrap().parse::<i64>().unwrap(),
    )
}

fn readin() -> (i64, i64, i64, i64, i64, i64) {
    let mut str = String::new();
    let _ = stdin().read_line(&mut str).unwrap();
    let mut iter = str.split_whitespace();
    (
        iter.next().unwrap().parse::<i64>().unwrap(),
        iter.next().unwrap().parse::<i64>().unwrap(),
        iter.next().unwrap().parse::<i64>().unwrap(),
        iter.next().unwrap().parse::<i64>().unwrap(),
        iter.next().unwrap().parse::<i64>().unwrap(),
        iter.next().unwrap().parse::<i64>().unwrap(),
    )
}
fn grid_01bfs(mat: &Vec<Vec<usize>>, start: (usize, usize)) -> Vec<Vec<usize>> {
    let h = mat.len();
    let w = mat[0].len();
    let mut res = vec![vec![INF as usize; (w) as usize]; (h) as usize];
    let mut q = VecDeque::new();
    q.push_back(start);
    res[start.0][start.1] = 0;
    while !q.is_empty() {
        let v = q.pop_front().unwrap();
        for i in -1..=1 {
            for j in -1..=1 {
                if (i * j as i32).abs() == 1 || (i == 0 && j == 0) {
                    continue;
                }
                if v.0 == 0 && i == -1 {
                    continue;
                }

                if v.0 == h - 1 && i == 1 {
                    continue;
                }

                if v.1 == 0 && j == -1 {
                    continue;
                }

                if v.1 == w - 1 && j == 1 {
                    continue;
                }
                let nv = ((v.0 as i32 + i) as usize, (v.1 as i32 + j) as usize);
                let mut d = 1;
                if mat[nv.0][nv.1] == 1 {
                    d = 1;
                } else {
                    d = 0;
                }
                if (res[nv.0][nv.1] > res[v.0][v.1] + d) {
                    res[nv.0][nv.1] = res[v.0][v.1] + d;
                    if d == 0 {
                        q.push_front(nv);
                    } else {
                        q.push_back(nv);
                    }
                }
            }
        }
    }

    return res;
}

fn solve() {
    let n: usize = read();
    let mut vec: Vec<i64> = read_vec();
    vec.sort();
    vec.reverse();
    let mut sum = 0;
    let mut a = 0;
    for i in 0..n {
        sum += vec[i];
        if i % 2 == 0 {
            a += vec[i];
        }
    }
    if sum < 0 {
        vec.reverse();
    }
    sum = 0;
    a = 0;
    for i in 0..n {
        sum += vec[i];
        if i % 2 == 0 {
            a += vec[i];
        }
    }

    if a >= sum {
        println!("{:?}", sum);
    } else if a < 0 {
        println!("{:?}", -1 * sum);
    } else {
        println!("{}", 2 * a - sum);
    }

    return;
}

fn main() {
    solve()
}