import 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;
        for(int i = 0; i <= n-1; i++){
            if(i%2 == 0){
                alice = alice + a[n-1-i];
            } else {
                bob = bob + a[n-1-i];
            }
        }
        System.out.print(alice - bob);
    }
} import java.util.*; util.* java 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;
        for(int i = 0; i <= n-1; i++){
            if(i%2 == 0){
                alice = alice + a[n-1-i];
            } else {
                bob = bob + a[n-1-i];
            }
        }
        System.out.print(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;
        for(int i = 0; i <= n-1; i++){
            if(i%2 == 0){
                alice = alice + a[n-1-i];
            } else {
                bob = bob + a[n-1-i];
            }
        }
        System.out.print(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;
        for(int i = 0; i <= n-1; i++){
            if(i%2 == 0){
                alice = alice + a[n-1-i];
            } else {
                bob = bob + a[n-1-i];
            }
        }
        System.out.print(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 for(int i = 0; i <= n-1; i++){
            if(i%2 == 0){
                alice = alice + a[n-1-i];
            } else {
                bob = bob + a[n-1-i];
            }
        } int i = 0; int i = 0; i 0 i <= n-1 i n-1 n 1 i++ i++ i {
            if(i%2 == 0){
                alice = alice + a[n-1-i];
            } else {
                bob = bob + a[n-1-i];
            }
        } {
            if(i%2 == 0){
                alice = alice + a[n-1-i];
            } else {
                bob = bob + a[n-1-i];
            }
        } if(i%2 == 0){
                alice = alice + a[n-1-i];
            } else {
                bob = bob + a[n-1-i];
            } i%2 == 0 i%2 i 2 0 {
                alice = alice + a[n-1-i];
            } alice = alice + a[n-1-i] alice alice + a[n-1-i] alice a[n-1-i] a n-1-i n-1-i n 1 i {
                bob = bob + a[n-1-i];
            } bob = bob + a[n-1-i] bob bob + a[n-1-i] bob a[n-1-i] a n-1-i n-1-i n 1 i System.out.print(alice - bob) System.out.print 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;
        for(int i = 0; i <= n-1; i++){
            if(i%2 == 0){
                alice = alice + a[n-1-i];
            } else {
                bob = bob + a[n-1-i];
            }
        }
        System.out.print(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;
        for(int i = 0; i <= n-1; i++){
            if(i%2 == 0){
                alice = alice + a[n-1-i];
            } else {
                bob = bob + a[n-1-i];
            }
        }
        System.out.print(alice - bob);
    }
} Main
import 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;
        for(int i = 0; i <= n-1; i++){
            if(i%2 == 0){
                alice = alice + a[n-1-i];
            } else {
                bob = bob + a[n-1-i];
            }
        }
        System.out.print(alice - bob);
    }
}