#include<bits/stdc++.h>
using namespace std;
#define REP(i,m,n) for(int i=(int)(m) ; i < (int) (n) ; ++i )
#define rep(i,n) REP(i,0,n)
typedef long long ll;

int main(){
    int n;
    cin>>n;
    ll a[n];
    rep(i,n)cin>>a[i];
    sort(a,a+n);
    ll ans=0;
    rep(i,n){
        if(ans%2)ans-=a[i];
        else ans+=a[i];
    }
    cout<<abs(ans)<<endl;
    return 0;
}