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

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		List<Integer> list = new ArrayList<>();
		int n = sc.nextInt();
		for(int i = 0; i < n; i++) {
			list.add(sc.nextInt());
		}
		Collections.sort(list);
		list.sort(Comparator.reverseOrder());
		int a = 0;
		int b = 0;
		for(int i = 0; i < list.size(); 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.Comparator; Comparator java.util import java.util.List; List java.util import java.util.Scanner; Scanner java.util public class Main {

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

public class Main {

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

}
