import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.Scanner;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author ky112233
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        BCardGameForTwo solver = new BCardGameForTwo();
        solver.solve(1, in, out);
        out.close();
    }

    static class BCardGameForTwo {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            int n = in.nextInt();
            int[] a = new int[n];
            for (int i = 0; i < n; i++) a[i] = in.nextInt();
            Arrays.sort(a);
            int alice = 0;
            int bob = 0;
            for (int i = n - 1; i >= 0; i--) {
                if ((n - 1 - i) % 2 == 0) alice += a[i];
                else bob += a[i];
            }
            out.println(alice - bob);
        }

    }
}
 import java.io.OutputStream; OutputStream java.io import java.io.IOException; IOException java.io import java.io.InputStream; InputStream java.io import java.io.PrintWriter; PrintWriter java.io import java.util.Arrays; Arrays java.util import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        BCardGameForTwo solver = new BCardGameForTwo();
        solver.solve(1, in, out);
        out.close();
    }

    static class BCardGameForTwo {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            int n = in.nextInt();
            int[] a = new int[n];
            for (int i = 0; i < n; i++) a[i] = in.nextInt();
            Arrays.sort(a);
            int alice = 0;
            int bob = 0;
            for (int i = n - 1; i >= 0; i--) {
                if ((n - 1 - i) % 2 == 0) alice += a[i];
                else bob += a[i];
            }
            out.println(alice - bob);
        }

    }
} Main public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        BCardGameForTwo solver = new BCardGameForTwo();
        solver.solve(1, in, out);
        out.close();
    } main {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        BCardGameForTwo solver = new BCardGameForTwo();
        solver.solve(1, in, out);
        out.close();
    } InputStream inputStream = System.in; inputStream System.in System System.in OutputStream outputStream = System.out; outputStream System.out System System.out Scanner in = new Scanner(inputStream); in new Scanner(inputStream) PrintWriter out = new PrintWriter(outputStream); out new PrintWriter(outputStream) BCardGameForTwo solver = new BCardGameForTwo(); solver new BCardGameForTwo() solver.solve(1, in, out) solver.solve solver 1 in out out.close() out.close out String[] args args static class BCardGameForTwo {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            int n = in.nextInt();
            int[] a = new int[n];
            for (int i = 0; i < n; i++) a[i] = in.nextInt();
            Arrays.sort(a);
            int alice = 0;
            int bob = 0;
            for (int i = n - 1; i >= 0; i--) {
                if ((n - 1 - i) % 2 == 0) alice += a[i];
                else bob += a[i];
            }
            out.println(alice - bob);
        }

    } BCardGameForTwo public void solve(int testNumber, Scanner in, PrintWriter out) {
            int n = in.nextInt();
            int[] a = new int[n];
            for (int i = 0; i < n; i++) a[i] = in.nextInt();
            Arrays.sort(a);
            int alice = 0;
            int bob = 0;
            for (int i = n - 1; i >= 0; i--) {
                if ((n - 1 - i) % 2 == 0) alice += a[i];
                else bob += a[i];
            }
            out.println(alice - bob);
        } solve {
            int n = in.nextInt();
            int[] a = new int[n];
            for (int i = 0; i < n; i++) a[i] = in.nextInt();
            Arrays.sort(a);
            int alice = 0;
            int bob = 0;
            for (int i = n - 1; i >= 0; i--) {
                if ((n - 1 - i) % 2 == 0) alice += a[i];
                else bob += a[i];
            }
            out.println(alice - bob);
        } int n = in.nextInt(); n in.nextInt() in.nextInt in int[] a = new int[n]; a new int[n] n for (int i = 0; i < n; i++) a[i] = in.nextInt(); int i = 0; int i = 0; i 0 i < n i n i++ i++ i a[i] = in.nextInt(); a[i] = in.nextInt() a[i] a i in.nextInt() in.nextInt in Arrays.sort(a) Arrays.sort Arrays a int alice = 0; alice 0 int bob = 0; bob 0 for (int i = n - 1; i >= 0; i--) {
                if ((n - 1 - i) % 2 == 0) alice += a[i];
                else bob += a[i];
            } int i = n - 1; int i = n - 1; i n - 1 n 1 i >= 0 i 0 i-- i-- i {
                if ((n - 1 - i) % 2 == 0) alice += a[i];
                else bob += a[i];
            } {
                if ((n - 1 - i) % 2 == 0) alice += a[i];
                else bob += a[i];
            } if ((n - 1 - i) % 2 == 0) alice += a[i];
                else bob += a[i]; (n - 1 - i) % 2 == 0 (n - 1 - i) % 2 (n - 1 - i) n - 1 - i n 1 i 2 0 alice += a[i] alice a[i] a i bob += a[i] bob a[i] a i out.println(alice - bob) out.println out alice - bob alice bob int testNumber testNumber Scanner in in PrintWriter out out public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        BCardGameForTwo solver = new BCardGameForTwo();
        solver.solve(1, in, out);
        out.close();
    }

    static class BCardGameForTwo {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            int n = in.nextInt();
            int[] a = new int[n];
            for (int i = 0; i < n; i++) a[i] = in.nextInt();
            Arrays.sort(a);
            int alice = 0;
            int bob = 0;
            for (int i = n - 1; i >= 0; i--) {
                if ((n - 1 - i) % 2 == 0) alice += a[i];
                else bob += a[i];
            }
            out.println(alice - bob);
        }

    }
} public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        BCardGameForTwo solver = new BCardGameForTwo();
        solver.solve(1, in, out);
        out.close();
    }

    static class BCardGameForTwo {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            int n = in.nextInt();
            int[] a = new int[n];
            for (int i = 0; i < n; i++) a[i] = in.nextInt();
            Arrays.sort(a);
            int alice = 0;
            int bob = 0;
            for (int i = n - 1; i >= 0; i--) {
                if ((n - 1 - i) % 2 == 0) alice += a[i];
                else bob += a[i];
            }
            out.println(alice - bob);
        }

    }
} Main
import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.Scanner;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author ky112233
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        BCardGameForTwo solver = new BCardGameForTwo();
        solver.solve(1, in, out);
        out.close();
    }

    static class BCardGameForTwo {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            int n = in.nextInt();
            int[] a = new int[n];
            for (int i = 0; i < n; i++) a[i] = in.nextInt();
            Arrays.sort(a);
            int alice = 0;
            int bob = 0;
            for (int i = n - 1; i >= 0; i--) {
                if ((n - 1 - i) % 2 == 0) alice += a[i];
                else bob += a[i];
            }
            out.println(alice - bob);
        }

    }
}

