#include <bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;
using ll = long long;
ll N;
vector<ll> A;

void solve(){
    set<ll> s;
    for(ll i = 0;i<N;i++){
        s.insert(A[i]);
    }
    ll X=0,Y=0;
    for(ll i = 0;i<N;i++){
        if(i%2==0){
            X += *s.begin();
            s.erase(s.begin());
        }else{
            Y -= *s.rbegin();
            s.erase(prev(s.end()));
        }
    }
    cout<<X-Y<<endl;
}

signed main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cin >> N;
    A.resize(N);
    for(ll i = 0; i < N; i++) cin >> A[i];
    solve();
}