import java.util.*;

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

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