import java.util.Arrays;
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();
		Integer[] a = new Integer[n];
		for(int i=0;i<n;i++) {
			a[i]=sc.nextInt();
		}
		Arrays.sort(a,Collections.reverseOrder());
		int alice=0;
		int bob = 0;
		int sum=0;
		for(int i=0;i<n;i++) {
			if(i%2 ==0) {
				alice+=a[i];
			}else {
				bob+=a[i];
			}
		}
		sum=alice-bob;
		System.out.println(sum);
	}
} import java.util.Arrays; Arrays 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();
		Integer[] a = new Integer[n];
		for(int i=0;i<n;i++) {
			a[i]=sc.nextInt();
		}
		Arrays.sort(a,Collections.reverseOrder());
		int alice=0;
		int bob = 0;
		int sum=0;
		for(int i=0;i<n;i++) {
			if(i%2 ==0) {
				alice+=a[i];
			}else {
				bob+=a[i];
			}
		}
		sum=alice-bob;
		System.out.println(sum);
	}
} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		Integer[] a = new Integer[n];
		for(int i=0;i<n;i++) {
			a[i]=sc.nextInt();
		}
		Arrays.sort(a,Collections.reverseOrder());
		int alice=0;
		int bob = 0;
		int sum=0;
		for(int i=0;i<n;i++) {
			if(i%2 ==0) {
				alice+=a[i];
			}else {
				bob+=a[i];
			}
		}
		sum=alice-bob;
		System.out.println(sum);
	} main {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		Integer[] a = new Integer[n];
		for(int i=0;i<n;i++) {
			a[i]=sc.nextInt();
		}
		Arrays.sort(a,Collections.reverseOrder());
		int alice=0;
		int bob = 0;
		int sum=0;
		for(int i=0;i<n;i++) {
			if(i%2 ==0) {
				alice+=a[i];
			}else {
				bob+=a[i];
			}
		}
		sum=alice-bob;
		System.out.println(sum);
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc Integer[] a = new Integer[n]; a new Integer[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,Collections.reverseOrder()) Arrays.sort Arrays a Collections.reverseOrder() Collections.reverseOrder Collections int alice=0; alice 0 int bob = 0; bob 0 int sum=0; sum 0 for(int i=0;i<n;i++) {
			if(i%2 ==0) {
				alice+=a[i];
			}else {
				bob+=a[i];
			}
		} int i=0; int i=0; i 0 i<n i n i++ i++ i {
			if(i%2 ==0) {
				alice+=a[i];
			}else {
				bob+=a[i];
			}
		} {
			if(i%2 ==0) {
				alice+=a[i];
			}else {
				bob+=a[i];
			}
		} if(i%2 ==0) {
				alice+=a[i];
			}else {
				bob+=a[i];
			} i%2 ==0 i%2 i 2 0 {
				alice+=a[i];
			} alice+=a[i] alice a[i] a i {
				bob+=a[i];
			} bob+=a[i] bob a[i] a i sum=alice-bob sum alice-bob alice bob System.out.println(sum) System.out.println System.out System System.out sum String[] args args public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		Integer[] a = new Integer[n];
		for(int i=0;i<n;i++) {
			a[i]=sc.nextInt();
		}
		Arrays.sort(a,Collections.reverseOrder());
		int alice=0;
		int bob = 0;
		int sum=0;
		for(int i=0;i<n;i++) {
			if(i%2 ==0) {
				alice+=a[i];
			}else {
				bob+=a[i];
			}
		}
		sum=alice-bob;
		System.out.println(sum);
	}
} public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		Integer[] a = new Integer[n];
		for(int i=0;i<n;i++) {
			a[i]=sc.nextInt();
		}
		Arrays.sort(a,Collections.reverseOrder());
		int alice=0;
		int bob = 0;
		int sum=0;
		for(int i=0;i<n;i++) {
			if(i%2 ==0) {
				alice+=a[i];
			}else {
				bob+=a[i];
			}
		}
		sum=alice-bob;
		System.out.println(sum);
	}
} Main
import java.util.Arrays;
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();
		Integer[] a = new Integer[n];
		for(int i=0;i<n;i++) {
			a[i]=sc.nextInt();
		}
		Arrays.sort(a,Collections.reverseOrder());
		int alice=0;
		int bob = 0;
		int sum=0;
		for(int i=0;i<n;i++) {
			if(i%2 ==0) {
				alice+=a[i];
			}else {
				bob+=a[i];
			}
		}
		sum=alice-bob;
		System.out.println(sum);
	}
}
