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

public class Main {

    public static void main(String[] args) {
        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;
        boolean isAlice = true;
        for (int i = a.length - 1; i != -1; i--) {
            if (isAlice) {
                alice += a[i];
            } else {
                bob += a[i];
            }
            isAlice = !isAlice;
        }

        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) {
        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;
        boolean isAlice = true;
        for (int i = a.length - 1; i != -1; i--) {
            if (isAlice) {
                alice += a[i];
            } else {
                bob += a[i];
            }
            isAlice = !isAlice;
        }

        System.out.println(alice - bob);
    }
} Main public static void main(String[] args) {
        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;
        boolean isAlice = true;
        for (int i = a.length - 1; i != -1; i--) {
            if (isAlice) {
                alice += a[i];
            } else {
                bob += a[i];
            }
            isAlice = !isAlice;
        }

        System.out.println(alice - bob);
    } main {
        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;
        boolean isAlice = true;
        for (int i = a.length - 1; i != -1; i--) {
            if (isAlice) {
                alice += a[i];
            } else {
                bob += a[i];
            }
            isAlice = !isAlice;
        }

        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 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 boolean isAlice = true; isAlice true for (int i = a.length - 1; i != -1; i--) {
            if (isAlice) {
                alice += a[i];
            } else {
                bob += a[i];
            }
            isAlice = !isAlice;
        } int i = a.length - 1; int i = a.length - 1; i a.length - 1 a.length a a.length 1 i != -1 i -1 1 i-- i-- i {
            if (isAlice) {
                alice += a[i];
            } else {
                bob += a[i];
            }
            isAlice = !isAlice;
        } {
            if (isAlice) {
                alice += a[i];
            } else {
                bob += a[i];
            }
            isAlice = !isAlice;
        } if (isAlice) {
                alice += a[i];
            } else {
                bob += a[i];
            } isAlice {
                alice += a[i];
            } alice += a[i] alice a[i] a i {
                bob += a[i];
            } bob += a[i] bob a[i] a i isAlice = !isAlice isAlice !isAlice isAlice 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();

        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;
        boolean isAlice = true;
        for (int i = a.length - 1; i != -1; i--) {
            if (isAlice) {
                alice += a[i];
            } else {
                bob += a[i];
            }
            isAlice = !isAlice;
        }

        System.out.println(alice - bob);
    }
} public class Main {

    public static void main(String[] args) {
        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;
        boolean isAlice = true;
        for (int i = a.length - 1; i != -1; i--) {
            if (isAlice) {
                alice += a[i];
            } else {
                bob += a[i];
            }
            isAlice = !isAlice;
        }

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

public class Main {

    public static void main(String[] args) {
        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;
        boolean isAlice = true;
        for (int i = a.length - 1; i != -1; i--) {
            if (isAlice) {
                alice += a[i];
            } else {
                bob += a[i];
            }
            isAlice = !isAlice;
        }

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