#include <bits/stdc++.h>
#define rep(i, a, n) for(int i = a; i < (int)(n); i++)
#define vi vector<int>
#define vs vector<string>
#define vvi vector<vector<int>>
#define vb vector<bool>
#define ll long long
#define dd double
using namespace std;

void faster() {
    ios::sync_with_stdio(false);
    cin.tie(0);
}

template <typename T>
void input(T &x) {
    cin >> x;
}
template <typename T, typename... Args>
void input(T &x, Args&... args) {
    cin >> x;
    input(args...);
}

template <typename T>
void sorts(vector<T>& vec) {
    sort(vec.begin(), vec.end());
}

template <typename T>
void rsorts(vector<T>& vec) {
    sort(vec.begin(), vec.end(), greater<T>());
}

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

int main() {
    faster();
    int n;
    input(n);
    vi nums(n);
    rep(i,0,n) input(nums[i]);

    rsorts(nums);

    ll first_sum = 0, second_sum = 0;
    
    int left = 0, right = n - 1;
    
    while (left <= right) {
        if (left <= right) {
            first_sum += nums[left];
            left++;
        }
        if (left <= right) {
            second_sum -= nums[right];
            right--;
        }

    }
    cout << first_sum - second_sum << endl;
}