#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using VI = vector<int>;
using VL = vector<ll>;
using VS = vector<string>;
template <class T>
using PQ = priority_queue<T, vector<T>, greater<T>>;
#define FOR(i, a, n) for (int i = (a); i < (n); ++i)
#define eFOR(i, a, n) for (int i = (a); i <= (n); ++i)
#define rFOR(i, a, n) for (int i = (n)-1; i >= (a); --i)
#define erFOR(i, a, n) for (int i = (n); i >= (a); --i)
#define each(i, a) for (auto &i : a)
#define SORT(a) sort(a.begin(), a.end())
#define rSORT(a) sort(a.rbegin(), a.rend())
#define fSORT(a, f) sort(a.begin(), a.end(), f)
#define all(a) a.begin(), a.end()
#define out(y, x) ((y) < 0 || h <= (y) || (x) < 0 || w <= (x))
#define tp(a, i) get<i>(a)
#define line cout << "-----------------------------\n"
#define ENDL(i, n) ((i) == (n)-1 ? "\n" : " ")
#define stop system("pause")
constexpr ll INF = 1000000000;
constexpr ll LLINF = 1LL << 60;
constexpr ll mod = 1000000007;
constexpr ll MOD = 998244353;
constexpr ld eps = 1e-10;
constexpr ld pi = 3.1415926535897932;
template <class T>
inline bool chmax(T &a, const T &b)
{
    if (a < b)
    {
        a = b;
        return true;
    }
    return false;
}
template <class T>
inline bool chmin(T &a, const T &b)
{
    if (a > b)
    {
        a = b;
        return true;
    }
    return false;
}
inline void init()
{
    cin.tie(nullptr);
    cout.tie(nullptr);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(15);
}
template <class T>
inline istream &operator>>(istream &is, vector<T> &v)
{
    for (auto &a : v)
        is >> a;
    return is;
}
template <class T>
inline istream &operator>>(istream &is, deque<T> &v)
{
    for (auto &a : v)
        is >> a;
    return is;
}
template <class T, class U>
inline istream &operator>>(istream &is, pair<T, U> &p)
{
    is >> p.first >> p.second;
    return is;
}
template <class T>
inline vector<T> vec(size_t a) { return vector<T>(a); }
template <class T>
inline vector<T> defvec(T def, size_t a) { return vector<T>(a, def); }
template <class T, class... Ts>
inline auto vec(size_t a, Ts... ts) { return vector<decltype(vec<T>(ts...))>(a, vec<T>(ts...)); }
template <class T, class... Ts>
inline auto defvec(T def, size_t a, Ts... ts) { return vector<decltype(defvec<T>(def, ts...))>(a, defvec<T>(def, ts...)); }
template <class T>
inline void print(const T &a) { cout << a << "\n"; }
template <class T, class... Ts>
inline void print(const T &a, const Ts &... ts)
{
    cout << a << " ";
    print(ts...);
}
template <class T>
inline void print(const vector<T> &v)
{
    for (int i = 0; i < v.size(); ++i)
        cout << v[i] << (i == v.size() - 1 ? "\n" : " ");
}
template <class T>
inline void print(const vector<vector<T>> &v)
{
    for (auto &a : v)
        print(a);
}
inline string reversed(const string &s)
{
    string t = s;
    reverse(all(t));
    return t;
}

int main()
{
    init();
    int n;
    cin >> n;
    VI a(n, 0);
    for (int i = 0; i < n; i++)
        cin >> a[i];
    // FOR(i, n, 0) { cin >> a[i]; }
    rSORT(a);
    int alice = 0, bob = 0;
    for (int i = 0; i < n; i++)
    {
        if (i % 2 == 0)
            alice += a[i];
        else
            bob += a[i];
    }
    cout << alice - bob << endl;
    return 0;
}

Measured memory_bytes: 3664