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

public class Main {

    public static void main(String[] args) {
        @SuppressWarnings("resource")
        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;
        for (int i = 0 ; i < n ; i++) {
            if (i % 2 == 0) {
                alice += a[n - 1 - i];
            } else {
                bob += a[n - 1 - i];
            }
        }
        System.out.println(alice - bob);
    }

} import java.util.Arrays; Arrays java.util import java.util.Scanner; Scanner java.util public class Main {

    public static void main(String[] args) {
        @SuppressWarnings("resource")
        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;
        for (int i = 0 ; i < n ; i++) {
            if (i % 2 == 0) {
                alice += a[n - 1 - i];
            } else {
                bob += a[n - 1 - i];
            }
        }
        System.out.println(alice - bob);
    }

} Main public static void main(String[] args) {
        @SuppressWarnings("resource")
        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;
        for (int i = 0 ; i < n ; i++) {
            if (i % 2 == 0) {
                alice += a[n - 1 - i];
            } else {
                bob += a[n - 1 - i];
            }
        }
        System.out.println(alice - bob);
    } main {
        @SuppressWarnings("resource")
        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;
        for (int i = 0 ; i < n ; i++) {
            if (i % 2 == 0) {
                alice += a[n - 1 - i];
            } else {
                bob += a[n - 1 - i];
            }
        }
        System.out.println(alice - bob);
    } @SuppressWarnings("resource")
        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 for (int i = 0 ; i < n ; i++) {
            if (i % 2 == 0) {
                alice += a[n - 1 - i];
            } else {
                bob += a[n - 1 - i];
            }
        } int i = 0 ; int i = 0 ; i 0 i < n i n i++ i++ i {
            if (i % 2 == 0) {
                alice += a[n - 1 - i];
            } else {
                bob += a[n - 1 - i];
            }
        } {
            if (i % 2 == 0) {
                alice += a[n - 1 - i];
            } else {
                bob += a[n - 1 - i];
            }
        } if (i % 2 == 0) {
                alice += a[n - 1 - i];
            } else {
                bob += a[n - 1 - i];
            } i % 2 == 0 i % 2 i 2 0 {
                alice += a[n - 1 - i];
            } alice += a[n - 1 - i] alice a[n - 1 - i] a n - 1 - i n - 1 - i n 1 i {
                bob += a[n - 1 - i];
            } bob += a[n - 1 - i] bob a[n - 1 - i] a n - 1 - i n - 1 - i n 1 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) {
        @SuppressWarnings("resource")
        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;
        for (int i = 0 ; i < n ; i++) {
            if (i % 2 == 0) {
                alice += a[n - 1 - i];
            } else {
                bob += a[n - 1 - i];
            }
        }
        System.out.println(alice - bob);
    }

} public class Main {

    public static void main(String[] args) {
        @SuppressWarnings("resource")
        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;
        for (int i = 0 ; i < n ; i++) {
            if (i % 2 == 0) {
                alice += a[n - 1 - i];
            } else {
                bob += a[n - 1 - i];
            }
        }
        System.out.println(alice - bob);
    }

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

public class Main {

    public static void main(String[] args) {
        @SuppressWarnings("resource")
        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;
        for (int i = 0 ; i < n ; i++) {
            if (i % 2 == 0) {
                alice += a[n - 1 - i];
            } else {
                bob += a[n - 1 - i];
            }
        }
        System.out.println(alice - bob);
    }

}