import java.util.Arrays;
import java.util.Scanner;
 
public 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 < a.length; i++) {
            a[i] = sc.nextInt();
        }
 
        int alice = 0;
        int bob = 0;
 
        Arrays.sort(a);
        int index = 0;
        for (int i = N - 1; i >= 0; i--) {
            if (index % 2 == 0)
                alice += a[i];
            else
                bob += a[i];
 
            index++;
        }
 
        System.out.println(alice - bob);
        sc.close();
    }
} import java.util.Arrays; Arrays java.util import java.util.Scanner; Scanner java.util public 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 < a.length; i++) {
            a[i] = sc.nextInt();
        }
 
        int alice = 0;
        int bob = 0;
 
        Arrays.sort(a);
        int index = 0;
        for (int i = N - 1; i >= 0; i--) {
            if (index % 2 == 0)
                alice += a[i];
            else
                bob += a[i];
 
            index++;
        }
 
        System.out.println(alice - bob);
        sc.close();
    }
} 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 < a.length; i++) {
            a[i] = sc.nextInt();
        }
 
        int alice = 0;
        int bob = 0;
 
        Arrays.sort(a);
        int index = 0;
        for (int i = N - 1; i >= 0; i--) {
            if (index % 2 == 0)
                alice += a[i];
            else
                bob += a[i];
 
            index++;
        }
 
        System.out.println(alice - bob);
        sc.close();
    } main {
        Scanner sc = new Scanner(System.in);
 
        int N = sc.nextInt();
        int[] a = new int[N];
 
        for (int i = 0; i < a.length; i++) {
            a[i] = sc.nextInt();
        }
 
        int alice = 0;
        int bob = 0;
 
        Arrays.sort(a);
        int index = 0;
        for (int i = N - 1; i >= 0; i--) {
            if (index % 2 == 0)
                alice += a[i];
            else
                bob += a[i];
 
            index++;
        }
 
        System.out.println(alice - bob);
        sc.close();
    } 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 < a.length; i++) {
            a[i] = sc.nextInt();
        } int i = 0; int i = 0; i 0 i < a.length i a.length a a.length i++ i++ i {
            a[i] = sc.nextInt();
        } {
            a[i] = sc.nextInt();
        } a[i] = sc.nextInt() a[i] a i sc.nextInt() sc.nextInt sc int alice = 0; alice 0 int bob = 0; bob 0 Arrays.sort(a) Arrays.sort Arrays a int index = 0; index 0 for (int i = N - 1; i >= 0; i--) {
            if (index % 2 == 0)
                alice += a[i];
            else
                bob += a[i];
 
            index++;
        } int i = N - 1; int i = N - 1; i N - 1 N 1 i >= 0 i 0 i-- i-- i {
            if (index % 2 == 0)
                alice += a[i];
            else
                bob += a[i];
 
            index++;
        } {
            if (index % 2 == 0)
                alice += a[i];
            else
                bob += a[i];
 
            index++;
        } if (index % 2 == 0)
                alice += a[i];
            else
                bob += a[i]; index % 2 == 0 index % 2 index 2 0 alice += a[i] alice a[i] a i bob += a[i] bob a[i] a i index++ index System.out.println(alice - bob) System.out.println System.out System System.out alice - bob alice bob sc.close() sc.close sc String[] args args public 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 < a.length; i++) {
            a[i] = sc.nextInt();
        }
 
        int alice = 0;
        int bob = 0;
 
        Arrays.sort(a);
        int index = 0;
        for (int i = N - 1; i >= 0; i--) {
            if (index % 2 == 0)
                alice += a[i];
            else
                bob += a[i];
 
            index++;
        }
 
        System.out.println(alice - bob);
        sc.close();
    }
} public 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 < a.length; i++) {
            a[i] = sc.nextInt();
        }
 
        int alice = 0;
        int bob = 0;
 
        Arrays.sort(a);
        int index = 0;
        for (int i = N - 1; i >= 0; i--) {
            if (index % 2 == 0)
                alice += a[i];
            else
                bob += a[i];
 
            index++;
        }
 
        System.out.println(alice - bob);
        sc.close();
    }
} Main
import java.util.Arrays;
import java.util.Scanner;
 
public 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 < a.length; i++) {
            a[i] = sc.nextInt();
        }
 
        int alice = 0;
        int bob = 0;
 
        Arrays.sort(a);
        int index = 0;
        for (int i = N - 1; i >= 0; i--) {
            if (index % 2 == 0)
                alice += a[i];
            else
                bob += a[i];
 
            index++;
        }
 
        System.out.println(alice - bob);
        sc.close();
    }
}