#include<bits/stdc++.h>
using namespace std;
using i64 = long long;
using u64 = unsigned long long;
using u32 = unsigned;
#define int long long
void solve(){
    int cnt=0;
    int n;
    cin >> n;
    vector<int> a(n);
    for (int i = 0; i < n;i++){
        cin >> a[i];
    }
    sort(a.begin(), a.end());
    int l = 0, r = n - 1;
    int x = 0, y = 0;
    while(cnt<n){
        if(cnt%2==0){
            x += a[r--];
        }
        else if(cnt&1){
            y += -1ll*a[l++];
        }
        cnt++;
    }
    cout << x - y << endl;
}


signed main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    solve();
    return 0;
}