import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        
        int a[] = new int[n];
        
        for(int i = 0; i < n; i++){
            a[i] = sc.nextInt();
        }

        Arrays.sort(a);

        int ans = 0;

        for(int i = n-1; i > -1; i--){
            if(i%2==0) ans += a[i];
            else ans -= a[i];
        }
        
        if(n%2==0) ans *= -1;
        
        System.out.println(ans);
    }
} import java.util.*; util.* java public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        
        int a[] = new int[n];
        
        for(int i = 0; i < n; i++){
            a[i] = sc.nextInt();
        }

        Arrays.sort(a);

        int ans = 0;

        for(int i = n-1; i > -1; i--){
            if(i%2==0) ans += a[i];
            else ans -= a[i];
        }
        
        if(n%2==0) ans *= -1;
        
        System.out.println(ans);
    }
} Main public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        
        int a[] = new int[n];
        
        for(int i = 0; i < n; i++){
            a[i] = sc.nextInt();
        }

        Arrays.sort(a);

        int ans = 0;

        for(int i = n-1; i > -1; i--){
            if(i%2==0) ans += a[i];
            else ans -= a[i];
        }
        
        if(n%2==0) ans *= -1;
        
        System.out.println(ans);
    } main {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        
        int a[] = new int[n];
        
        for(int i = 0; i < n; i++){
            a[i] = sc.nextInt();
        }

        Arrays.sort(a);

        int ans = 0;

        for(int i = n-1; i > -1; i--){
            if(i%2==0) ans += a[i];
            else ans -= a[i];
        }
        
        if(n%2==0) ans *= -1;
        
        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 int a[] = new int[n]; a new int[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) Arrays.sort Arrays a int ans = 0; ans 0 for(int i = n-1; i > -1; i--){
            if(i%2==0) ans += a[i];
            else ans -= a[i];
        } int i = n-1; int i = n-1; i n-1 n 1 i > -1 i -1 1 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] a i ans -= a[i] ans a[i] a i if(n%2==0) ans *= -1; n%2==0 n%2 n 2 0 ans *= -1 ans -1 1 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();
        
        int a[] = new int[n];
        
        for(int i = 0; i < n; i++){
            a[i] = sc.nextInt();
        }

        Arrays.sort(a);

        int ans = 0;

        for(int i = n-1; i > -1; i--){
            if(i%2==0) ans += a[i];
            else ans -= a[i];
        }
        
        if(n%2==0) ans *= -1;
        
        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();
        
        int a[] = new int[n];
        
        for(int i = 0; i < n; i++){
            a[i] = sc.nextInt();
        }

        Arrays.sort(a);

        int ans = 0;

        for(int i = n-1; i > -1; i--){
            if(i%2==0) ans += a[i];
            else ans -= a[i];
        }
        
        if(n%2==0) ans *= -1;
        
        System.out.println(ans);
    }
} Main
import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        
        int a[] = new int[n];
        
        for(int i = 0; i < n; i++){
            a[i] = sc.nextInt();
        }

        Arrays.sort(a);

        int ans = 0;

        for(int i = n-1; i > -1; i--){
            if(i%2==0) ans += a[i];
            else ans -= a[i];
        }
        
        if(n%2==0) ans *= -1;
        
        System.out.println(ans);
    }
}
