#include<iostream>
#include<set> 
#include<algorithm>
#include<vector>
#include<string>
#include<set>
#include<map>
#include<numeric>
#include<queue>
#include<cmath>
#include <unordered_set>
#include<cassert>
using namespace std;
typedef long long ll;
const ll INF=1LL<<60;
typedef pair<ll,int> P;
typedef pair<int,P> PP;
const ll MOD=1e9+7;


int main(){

    int N;
    cin>>N;
    vector<ll> c(N);
    for(int i=0;i<N;i++){
        cin>>c[i];
    }

    sort(c.begin(),c.end());
    reverse(c.begin(),c.end());

    vector<ll> sum(2,0);
    for(int i=0;i<N;i++){
        sum[i%2]+=c[i];
    }

    //ll d=sum[0] - sum[1];//abs(sum[0]) - abs(sum[1]);

    ll d=abs(sum[0]) - abs(sum[1]);


    cout<<d<<endl;




}