#include<bits/stdc++.h>
#define rep(i,N) for(int i=0;i<(N);i++)
#define rrep(i, n) for (int i = (int)n-1; i >= 0; --i)
#define FOR(i,a,b) for(int i=(a);i<(b);i++)
using namespace std;
const long long MOD = 1e9 + 7;
const long long INF = 1e12;
const int inf = 1e9;
const int mod = 1e9+7;
typedef long long ll;
typedef pair<ll,int> P;
typedef set<int> S;

template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }


int main(){
    int n;
    cin >> n;

    vector<ll> a(n);
    rep(i, n) cin >> a[i];

    if(accumulate(a.begin(), a.end(), 0) < 0){
        rep(i, n) a[i] = -1 * a[i];
    }

    sort(a.rbegin(), a.rend());

    ll sum_a = 0, sum_b = 0;

    rep(i,n){
        if(i%2 == 0){
            sum_a += a[i];
        }else{
            sum_b += a[i];
        }
    }

    cout << abs(sum_a) - abs(sum_b) << endl;

    return 0;
}