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

import static java.util.Comparator.reverseOrder;


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

        Arrays.sort(a, Comparator.reverseOrder());

        int alice = 0;
        int bob = 0;
        boolean b = true;
        for (Integer tmp : a) {
            if (b) {
                alice += tmp;
            }
            else {
                bob+= tmp;
            }
            b =!b;
        }

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

        Arrays.sort(a, Comparator.reverseOrder());

        int alice = 0;
        int bob = 0;
        boolean b = true;
        for (Integer tmp : a) {
            if (b) {
                alice += tmp;
            }
            else {
                bob+= tmp;
            }
            b =!b;
        }

        System.out.println(alice - bob);
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        Integer[] a = new Integer[n];
        for (int i = 0; i < n; i++) {
            a[i] = sc.nextInt();
        }

        Arrays.sort(a, Comparator.reverseOrder());

        int alice = 0;
        int bob = 0;
        boolean b = true;
        for (Integer tmp : a) {
            if (b) {
                alice += tmp;
            }
            else {
                bob+= tmp;
            }
            b =!b;
        }

        System.out.println(alice - bob);
    } main {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        Integer[] a = new Integer[n];
        for (int i = 0; i < n; i++) {
            a[i] = sc.nextInt();
        }

        Arrays.sort(a, Comparator.reverseOrder());

        int alice = 0;
        int bob = 0;
        boolean b = true;
        for (Integer tmp : a) {
            if (b) {
                alice += tmp;
            }
            else {
                bob+= tmp;
            }
            b =!b;
        }

        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 Integer[] a = new Integer[n]; a new Integer[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, Comparator.reverseOrder()) Arrays.sort Arrays a Comparator.reverseOrder() Comparator.reverseOrder Comparator int alice = 0; alice 0 int bob = 0; bob 0 boolean b = true; b true for (Integer tmp : a) {
            if (b) {
                alice += tmp;
            }
            else {
                bob+= tmp;
            }
            b =!b;
        } Integer tmp a {
            if (b) {
                alice += tmp;
            }
            else {
                bob+= tmp;
            }
            b =!b;
        } {
            if (b) {
                alice += tmp;
            }
            else {
                bob+= tmp;
            }
            b =!b;
        } if (b) {
                alice += tmp;
            }
            else {
                bob+= tmp;
            } b {
                alice += tmp;
            } alice += tmp alice tmp {
                bob+= tmp;
            } bob+= tmp bob tmp b =!b b !b b 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 sc = new Scanner(System.in);
        int n = sc.nextInt();
        Integer[] a = new Integer[n];
        for (int i = 0; i < n; i++) {
            a[i] = sc.nextInt();
        }

        Arrays.sort(a, Comparator.reverseOrder());

        int alice = 0;
        int bob = 0;
        boolean b = true;
        for (Integer tmp : a) {
            if (b) {
                alice += tmp;
            }
            else {
                bob+= tmp;
            }
            b =!b;
        }

        System.out.println(alice - bob);
    }
} public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        Integer[] a = new Integer[n];
        for (int i = 0; i < n; i++) {
            a[i] = sc.nextInt();
        }

        Arrays.sort(a, Comparator.reverseOrder());

        int alice = 0;
        int bob = 0;
        boolean b = true;
        for (Integer tmp : a) {
            if (b) {
                alice += tmp;
            }
            else {
                bob+= tmp;
            }
            b =!b;
        }

        System.out.println(alice - bob);
    }
} Main
import java.util.Arrays;
import java.util.Comparator;
import java.util.Scanner;

import static java.util.Comparator.reverseOrder;


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

        Arrays.sort(a, Comparator.reverseOrder());

        int alice = 0;
        int bob = 0;
        boolean b = true;
        for (Integer tmp : a) {
            if (b) {
                alice += tmp;
            }
            else {
                bob+= tmp;
            }
            b =!b;
        }

        System.out.println(alice - bob);
    }
}