import java.util.*;
import java.util.Collections;

public class Main {
    public static void main(String[] args) throws Exception {
        
        Scanner sc = new Scanner(System.in);
        int N= sc.nextInt();
        Integer ans=0;
        Integer[] A= new Integer[N];
        
        
        for(int i=0;i<N;i++){
            A[i]=sc.nextInt();
        }
        
        Arrays.sort(A, Collections.reverseOrder());
        
        for(int i=0;i<N;i++){
            if(i%2==0){
                ans+=A[i];
            }else{
                ans-=A[i];
            }
        }
        
        System.out.println(ans);
    }
} import java.util.*; util.* java import java.util.Collections; Collections java.util public class Main {
    public static void main(String[] args) throws Exception {
        
        Scanner sc = new Scanner(System.in);
        int N= sc.nextInt();
        Integer ans=0;
        Integer[] A= new Integer[N];
        
        
        for(int i=0;i<N;i++){
            A[i]=sc.nextInt();
        }
        
        Arrays.sort(A, Collections.reverseOrder());
        
        for(int i=0;i<N;i++){
            if(i%2==0){
                ans+=A[i];
            }else{
                ans-=A[i];
            }
        }
        
        System.out.println(ans);
    }
} Main public static void main(String[] args) throws Exception {
        
        Scanner sc = new Scanner(System.in);
        int N= sc.nextInt();
        Integer ans=0;
        Integer[] A= new Integer[N];
        
        
        for(int i=0;i<N;i++){
            A[i]=sc.nextInt();
        }
        
        Arrays.sort(A, Collections.reverseOrder());
        
        for(int i=0;i<N;i++){
            if(i%2==0){
                ans+=A[i];
            }else{
                ans-=A[i];
            }
        }
        
        System.out.println(ans);
    } main {
        
        Scanner sc = new Scanner(System.in);
        int N= sc.nextInt();
        Integer ans=0;
        Integer[] A= new Integer[N];
        
        
        for(int i=0;i<N;i++){
            A[i]=sc.nextInt();
        }
        
        Arrays.sort(A, Collections.reverseOrder());
        
        for(int i=0;i<N;i++){
            if(i%2==0){
                ans+=A[i];
            }else{
                ans-=A[i];
            }
        }
        
        System.out.println(ans);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int N= sc.nextInt(); N sc.nextInt() sc.nextInt sc Integer ans=0; ans 0 Integer[] A= new Integer[N]; A new Integer[N] N for(int i=0;i<N;i++){
            A[i]=sc.nextInt();
        } int i=0; int i=0; i 0 i<N i N i++ i++ i {
            A[i]=sc.nextInt();
        } {
            A[i]=sc.nextInt();
        } A[i]=sc.nextInt() A[i] A i sc.nextInt() sc.nextInt sc Arrays.sort(A, Collections.reverseOrder()) Arrays.sort Arrays A Collections.reverseOrder() Collections.reverseOrder Collections for(int i=0;i<N;i++){
            if(i%2==0){
                ans+=A[i];
            }else{
                ans-=A[i];
            }
        } int i=0; int i=0; i 0 i<N i N i++ i++ i {
            if(i%2==0){
                ans+=A[i];
            }else{
                ans-=A[i];
            }
        } {
            if(i%2==0){
                ans+=A[i];
            }else{
                ans-=A[i];
            }
        } if(i%2==0){
                ans+=A[i];
            }else{
                ans-=A[i];
            } i%2==0 i%2 i 2 0 {
                ans+=A[i];
            } ans+=A[i] ans A[i] A i {
                ans-=A[i];
            } ans-=A[i] ans A[i] A i System.out.println(ans) System.out.println System.out System System.out ans String[] args args public class Main {
    public static void main(String[] args) throws Exception {
        
        Scanner sc = new Scanner(System.in);
        int N= sc.nextInt();
        Integer ans=0;
        Integer[] A= new Integer[N];
        
        
        for(int i=0;i<N;i++){
            A[i]=sc.nextInt();
        }
        
        Arrays.sort(A, Collections.reverseOrder());
        
        for(int i=0;i<N;i++){
            if(i%2==0){
                ans+=A[i];
            }else{
                ans-=A[i];
            }
        }
        
        System.out.println(ans);
    }
} public class Main {
    public static void main(String[] args) throws Exception {
        
        Scanner sc = new Scanner(System.in);
        int N= sc.nextInt();
        Integer ans=0;
        Integer[] A= new Integer[N];
        
        
        for(int i=0;i<N;i++){
            A[i]=sc.nextInt();
        }
        
        Arrays.sort(A, Collections.reverseOrder());
        
        for(int i=0;i<N;i++){
            if(i%2==0){
                ans+=A[i];
            }else{
                ans-=A[i];
            }
        }
        
        System.out.println(ans);
    }
} Main
import java.util.*;
import java.util.Collections;

public class Main {
    public static void main(String[] args) throws Exception {
        
        Scanner sc = new Scanner(System.in);
        int N= sc.nextInt();
        Integer ans=0;
        Integer[] A= new Integer[N];
        
        
        for(int i=0;i<N;i++){
            A[i]=sc.nextInt();
        }
        
        Arrays.sort(A, Collections.reverseOrder());
        
        for(int i=0;i<N;i++){
            if(i%2==0){
                ans+=A[i];
            }else{
                ans-=A[i];
            }
        }
        
        System.out.println(ans);
    }
}
