import java.util.Arrays;
import java.util.Collections;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        Integer[] a = new Integer[n];
        for (int i = 0; i < n; i++) {
            a[i] = scanner.nextInt();
        }
        Arrays.sort(a, Collections.reverseOrder());
        int alice = 0;
        int bob = 0;
        for (int i =0;i<n;i++){
            if(i %2 == 0) {
                alice += a[i];
            } else{
                bob += a[i];
            }
        }
        System.out.println(alice - bob);

    }
} import java.util.Arrays; Arrays java.util import java.util.Collections; Collections java.util import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        Integer[] a = new Integer[n];
        for (int i = 0; i < n; i++) {
            a[i] = scanner.nextInt();
        }
        Arrays.sort(a, Collections.reverseOrder());
        int alice = 0;
        int bob = 0;
        for (int i =0;i<n;i++){
            if(i %2 == 0) {
                alice += a[i];
            } else{
                bob += a[i];
            }
        }
        System.out.println(alice - bob);

    }
} Main public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        Integer[] a = new Integer[n];
        for (int i = 0; i < n; i++) {
            a[i] = scanner.nextInt();
        }
        Arrays.sort(a, Collections.reverseOrder());
        int alice = 0;
        int bob = 0;
        for (int i =0;i<n;i++){
            if(i %2 == 0) {
                alice += a[i];
            } else{
                bob += a[i];
            }
        }
        System.out.println(alice - bob);

    } main {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        Integer[] a = new Integer[n];
        for (int i = 0; i < n; i++) {
            a[i] = scanner.nextInt();
        }
        Arrays.sort(a, Collections.reverseOrder());
        int alice = 0;
        int bob = 0;
        for (int i =0;i<n;i++){
            if(i %2 == 0) {
                alice += a[i];
            } else{
                bob += a[i];
            }
        }
        System.out.println(alice - bob);

    } Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) int n = scanner.nextInt(); n scanner.nextInt() scanner.nextInt scanner Integer[] a = new Integer[n]; a new Integer[n] n for (int i = 0; i < n; i++) {
            a[i] = scanner.nextInt();
        } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
            a[i] = scanner.nextInt();
        } {
            a[i] = scanner.nextInt();
        } a[i] = scanner.nextInt() a[i] a i scanner.nextInt() scanner.nextInt scanner Arrays.sort(a, Collections.reverseOrder()) Arrays.sort Arrays a Collections.reverseOrder() Collections.reverseOrder Collections int alice = 0; alice 0 int bob = 0; bob 0 for (int i =0;i<n;i++){
            if(i %2 == 0) {
                alice += a[i];
            } else{
                bob += a[i];
            }
        } int i =0; int i =0; i 0 i<n i n i++ i++ i {
            if(i %2 == 0) {
                alice += a[i];
            } else{
                bob += a[i];
            }
        } {
            if(i %2 == 0) {
                alice += a[i];
            } else{
                bob += a[i];
            }
        } if(i %2 == 0) {
                alice += a[i];
            } else{
                bob += a[i];
            } i %2 == 0 i %2 i 2 0 {
                alice += a[i];
            } alice += a[i] alice a[i] a i {
                bob += a[i];
            } bob += a[i] bob a[i] a i System.out.println(alice - bob) System.out.println System.out System System.out alice - bob alice bob String[] args args public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        Integer[] a = new Integer[n];
        for (int i = 0; i < n; i++) {
            a[i] = scanner.nextInt();
        }
        Arrays.sort(a, Collections.reverseOrder());
        int alice = 0;
        int bob = 0;
        for (int i =0;i<n;i++){
            if(i %2 == 0) {
                alice += a[i];
            } else{
                bob += a[i];
            }
        }
        System.out.println(alice - bob);

    }
} public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        Integer[] a = new Integer[n];
        for (int i = 0; i < n; i++) {
            a[i] = scanner.nextInt();
        }
        Arrays.sort(a, Collections.reverseOrder());
        int alice = 0;
        int bob = 0;
        for (int i =0;i<n;i++){
            if(i %2 == 0) {
                alice += a[i];
            } else{
                bob += a[i];
            }
        }
        System.out.println(alice - bob);

    }
} Main
import java.util.Arrays;
import java.util.Collections;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        Integer[] a = new Integer[n];
        for (int i = 0; i < n; i++) {
            a[i] = scanner.nextInt();
        }
        Arrays.sort(a, Collections.reverseOrder());
        int alice = 0;
        int bob = 0;
        for (int i =0;i<n;i++){
            if(i %2 == 0) {
                alice += a[i];
            } else{
                bob += a[i];
            }
        }
        System.out.println(alice - bob);

    }
}
