import java.util.*;
class Main {
    public static void main(String[] args) {
        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 alice = 0;
        int bob = 0;
        boolean f = false;
        for(int i = N-1; i>=0; i--) {
            if(f) bob += a[i];
            else alice += a[i];
            f = !f;
        }
        System.out.println(alice-bob);


    }
} import java.util.*; util.* java class Main {
    public static void main(String[] args) {
        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 alice = 0;
        int bob = 0;
        boolean f = false;
        for(int i = N-1; i>=0; i--) {
            if(f) bob += a[i];
            else alice += a[i];
            f = !f;
        }
        System.out.println(alice-bob);


    }
} Main public static void main(String[] args) {
        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 alice = 0;
        int bob = 0;
        boolean f = false;
        for(int i = N-1; i>=0; i--) {
            if(f) bob += a[i];
            else alice += a[i];
            f = !f;
        }
        System.out.println(alice-bob);


    } 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 alice = 0;
        int bob = 0;
        boolean f = false;
        for(int i = N-1; i>=0; i--) {
            if(f) bob += a[i];
            else alice += a[i];
            f = !f;
        }
        System.out.println(alice-bob);


    } 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 alice = 0; alice 0 int bob = 0; bob 0 boolean f = false; f false for(int i = N-1; i>=0; i--) {
            if(f) bob += a[i];
            else alice += a[i];
            f = !f;
        } int i = N-1; int i = N-1; i N-1 N 1 i>=0 i 0 i-- i-- i {
            if(f) bob += a[i];
            else alice += a[i];
            f = !f;
        } {
            if(f) bob += a[i];
            else alice += a[i];
            f = !f;
        } if(f) bob += a[i];
            else alice += a[i]; f bob += a[i] bob a[i] a i alice += a[i] alice a[i] a i f = !f f !f f System.out.println(alice-bob) System.out.println System.out System System.out alice-bob alice bob String[] args args
import java.util.*;
class Main {
    public static void main(String[] args) {
        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 alice = 0;
        int bob = 0;
        boolean f = false;
        for(int i = N-1; i>=0; i--) {
            if(f) bob += a[i];
            else alice += a[i];
            f = !f;
        }
        System.out.println(alice-bob);


    }
}