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

public class Main {

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

} import java.util.ArrayList; ArrayList java.util import java.util.Collections; Collections 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);
		int n = sc.nextInt();
		List<Integer> list = new ArrayList<Integer>();
		for(int i = 0; i < n; i++) {
			list.add(sc.nextInt());
		}
		Collections.sort(list);
		Collections.reverse(list);
		int result = 0;
		for(int i = 0; i < n; i++) {
			if(i == 0 || i % 2 == 0) {
				result += list.get(i);
			} else {
				result -= list.get(i);
			}
		}
		System.out.println(result);
	}

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

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

} public class Main {

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

} Main

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

public class Main {

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

}
