import java.util.ArrayList;
import java.util.Collections;
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        ArrayList<Integer> list = new ArrayList<>();
        for (int i = 0; i < n; i++) {
            list.add(sc.nextInt());
        }
        Collections.sort(list);
        Collections.reverse(list);
        int a = 0;
        int b = 0;
        for (int i = 0; i < n; i++) {
            if(i % 2 == 0) a += list.get(i);
            else b += list.get(i);
        }
        System.out.println(a - b);
    }
} import java.util.ArrayList; ArrayList java.util import java.util.Collections; Collections 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();
        ArrayList<Integer> list = new ArrayList<>();
        for (int i = 0; i < n; i++) {
            list.add(sc.nextInt());
        }
        Collections.sort(list);
        Collections.reverse(list);
        int a = 0;
        int b = 0;
        for (int i = 0; i < n; i++) {
            if(i % 2 == 0) a += list.get(i);
            else b += list.get(i);
        }
        System.out.println(a - b);
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        ArrayList<Integer> list = new ArrayList<>();
        for (int i = 0; i < n; i++) {
            list.add(sc.nextInt());
        }
        Collections.sort(list);
        Collections.reverse(list);
        int a = 0;
        int b = 0;
        for (int i = 0; i < n; i++) {
            if(i % 2 == 0) a += list.get(i);
            else b += list.get(i);
        }
        System.out.println(a - b);
    } main {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        ArrayList<Integer> list = new ArrayList<>();
        for (int i = 0; i < n; i++) {
            list.add(sc.nextInt());
        }
        Collections.sort(list);
        Collections.reverse(list);
        int a = 0;
        int b = 0;
        for (int i = 0; i < n; i++) {
            if(i % 2 == 0) a += list.get(i);
            else b += list.get(i);
        }
        System.out.println(a - b);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc ArrayList<Integer> list = new ArrayList<>(); list new ArrayList<>() for (int i = 0; i < n; i++) {
            list.add(sc.nextInt());
        } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
            list.add(sc.nextInt());
        } {
            list.add(sc.nextInt());
        } list.add(sc.nextInt()) list.add list sc.nextInt() sc.nextInt sc Collections.sort(list) Collections.sort Collections list Collections.reverse(list) Collections.reverse Collections list int a = 0; a 0 int b = 0; b 0 for (int i = 0; i < n; i++) {
            if(i % 2 == 0) a += list.get(i);
            else b += list.get(i);
        } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
            if(i % 2 == 0) a += list.get(i);
            else b += list.get(i);
        } {
            if(i % 2 == 0) a += list.get(i);
            else b += list.get(i);
        } if(i % 2 == 0) a += list.get(i);
            else b += list.get(i); i % 2 == 0 i % 2 i 2 0 a += list.get(i) a list.get(i) list.get list i b += list.get(i) b list.get(i) list.get list i System.out.println(a - b) System.out.println System.out System System.out a - b a b String[] args args public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        ArrayList<Integer> list = new ArrayList<>();
        for (int i = 0; i < n; i++) {
            list.add(sc.nextInt());
        }
        Collections.sort(list);
        Collections.reverse(list);
        int a = 0;
        int b = 0;
        for (int i = 0; i < n; i++) {
            if(i % 2 == 0) a += list.get(i);
            else b += list.get(i);
        }
        System.out.println(a - b);
    }
} public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        ArrayList<Integer> list = new ArrayList<>();
        for (int i = 0; i < n; i++) {
            list.add(sc.nextInt());
        }
        Collections.sort(list);
        Collections.reverse(list);
        int a = 0;
        int b = 0;
        for (int i = 0; i < n; i++) {
            if(i % 2 == 0) a += list.get(i);
            else b += list.get(i);
        }
        System.out.println(a - b);
    }
} Main
import java.util.ArrayList;
import java.util.Collections;
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        ArrayList<Integer> list = new ArrayList<>();
        for (int i = 0; i < n; i++) {
            list.add(sc.nextInt());
        }
        Collections.sort(list);
        Collections.reverse(list);
        int a = 0;
        int b = 0;
        for (int i = 0; i < n; i++) {
            if(i % 2 == 0) a += list.get(i);
            else b += list.get(i);
        }
        System.out.println(a - b);
    }
}