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);
		Integer n = sc.nextInt();
		List<Integer> numbers = new ArrayList<Integer>(n);
		for(int i = 1; i <= n; i++) {
			numbers.add(sc.nextInt());
		}
		Collections.sort(numbers, Collections.reverseOrder());
		
		Integer a = 0;
		Integer b = 0;
		for(int i = 0; i < n; i ++) {
			if(i % 2 == 0) {
				a += numbers.get(i);
			} else {
				b += numbers.get(i);
			}
		}
		System.out.println(a - b);
	}
} 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);
		Integer n = sc.nextInt();
		List<Integer> numbers = new ArrayList<Integer>(n);
		for(int i = 1; i <= n; i++) {
			numbers.add(sc.nextInt());
		}
		Collections.sort(numbers, Collections.reverseOrder());
		
		Integer a = 0;
		Integer b = 0;
		for(int i = 0; i < n; i ++) {
			if(i % 2 == 0) {
				a += numbers.get(i);
			} else {
				b += numbers.get(i);
			}
		}
		System.out.println(a - b);
	}
} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		Integer n = sc.nextInt();
		List<Integer> numbers = new ArrayList<Integer>(n);
		for(int i = 1; i <= n; i++) {
			numbers.add(sc.nextInt());
		}
		Collections.sort(numbers, Collections.reverseOrder());
		
		Integer a = 0;
		Integer b = 0;
		for(int i = 0; i < n; i ++) {
			if(i % 2 == 0) {
				a += numbers.get(i);
			} else {
				b += numbers.get(i);
			}
		}
		System.out.println(a - b);
	} main {
		Scanner sc = new Scanner(System.in);
		Integer n = sc.nextInt();
		List<Integer> numbers = new ArrayList<Integer>(n);
		for(int i = 1; i <= n; i++) {
			numbers.add(sc.nextInt());
		}
		Collections.sort(numbers, Collections.reverseOrder());
		
		Integer a = 0;
		Integer b = 0;
		for(int i = 0; i < n; i ++) {
			if(i % 2 == 0) {
				a += numbers.get(i);
			} else {
				b += numbers.get(i);
			}
		}
		System.out.println(a - b);
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) Integer n = sc.nextInt(); n sc.nextInt() sc.nextInt sc List<Integer> numbers = new ArrayList<Integer>(n); numbers new ArrayList<Integer>(n) for(int i = 1; i <= n; i++) {
			numbers.add(sc.nextInt());
		} int i = 1; int i = 1; i 1 i <= n i n i++ i++ i {
			numbers.add(sc.nextInt());
		} {
			numbers.add(sc.nextInt());
		} numbers.add(sc.nextInt()) numbers.add numbers sc.nextInt() sc.nextInt sc Collections.sort(numbers, Collections.reverseOrder()) Collections.sort Collections numbers Collections.reverseOrder() Collections.reverseOrder Collections Integer a = 0; a 0 Integer b = 0; b 0 for(int i = 0; i < n; i ++) {
			if(i % 2 == 0) {
				a += numbers.get(i);
			} else {
				b += numbers.get(i);
			}
		} int i = 0; int i = 0; i 0 i < n i n i ++ i ++ i {
			if(i % 2 == 0) {
				a += numbers.get(i);
			} else {
				b += numbers.get(i);
			}
		} {
			if(i % 2 == 0) {
				a += numbers.get(i);
			} else {
				b += numbers.get(i);
			}
		} if(i % 2 == 0) {
				a += numbers.get(i);
			} else {
				b += numbers.get(i);
			} i % 2 == 0 i % 2 i 2 0 {
				a += numbers.get(i);
			} a += numbers.get(i) a numbers.get(i) numbers.get numbers i {
				b += numbers.get(i);
			} b += numbers.get(i) b numbers.get(i) numbers.get numbers 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);
		Integer n = sc.nextInt();
		List<Integer> numbers = new ArrayList<Integer>(n);
		for(int i = 1; i <= n; i++) {
			numbers.add(sc.nextInt());
		}
		Collections.sort(numbers, Collections.reverseOrder());
		
		Integer a = 0;
		Integer b = 0;
		for(int i = 0; i < n; i ++) {
			if(i % 2 == 0) {
				a += numbers.get(i);
			} else {
				b += numbers.get(i);
			}
		}
		System.out.println(a - b);
	}
} public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		Integer n = sc.nextInt();
		List<Integer> numbers = new ArrayList<Integer>(n);
		for(int i = 1; i <= n; i++) {
			numbers.add(sc.nextInt());
		}
		Collections.sort(numbers, Collections.reverseOrder());
		
		Integer a = 0;
		Integer b = 0;
		for(int i = 0; i < n; i ++) {
			if(i % 2 == 0) {
				a += numbers.get(i);
			} else {
				b += numbers.get(i);
			}
		}
		System.out.println(a - b);
	}
} 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);
		Integer n = sc.nextInt();
		List<Integer> numbers = new ArrayList<Integer>(n);
		for(int i = 1; i <= n; i++) {
			numbers.add(sc.nextInt());
		}
		Collections.sort(numbers, Collections.reverseOrder());
		
		Integer a = 0;
		Integer b = 0;
		for(int i = 0; i < n; i ++) {
			if(i % 2 == 0) {
				a += numbers.get(i);
			} else {
				b += numbers.get(i);
			}
		}
		System.out.println(a - b);
	}
}