import java.util.Arrays;
import java.util.Scanner;

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 = 1; i < N+1; i++) {
			if(i % 2 == 1) {
				Alice += a[N-i];
			}else {
				Bob += a[N-i];
			}
		}
		System.out.println(Alice - Bob);
	}

} import java.util.Arrays; Arrays 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();
		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 = 1; i < N+1; i++) {
			if(i % 2 == 1) {
				Alice += a[N-i];
			}else {
				Bob += a[N-i];
			}
		}
		System.out.println(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 = 1; i < N+1; i++) {
			if(i % 2 == 1) {
				Alice += a[N-i];
			}else {
				Bob += a[N-i];
			}
		}
		System.out.println(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 = 1; i < N+1; i++) {
			if(i % 2 == 1) {
				Alice += a[N-i];
			}else {
				Bob += a[N-i];
			}
		}
		System.out.println(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 = 1; i < N+1; i++) {
			if(i % 2 == 1) {
				Alice += a[N-i];
			}else {
				Bob += a[N-i];
			}
		} int i = 1; int i = 1; i 1 i < N+1 i N+1 N 1 i++ i++ i {
			if(i % 2 == 1) {
				Alice += a[N-i];
			}else {
				Bob += a[N-i];
			}
		} {
			if(i % 2 == 1) {
				Alice += a[N-i];
			}else {
				Bob += a[N-i];
			}
		} if(i % 2 == 1) {
				Alice += a[N-i];
			}else {
				Bob += a[N-i];
			} i % 2 == 1 i % 2 i 2 1 {
				Alice += a[N-i];
			} Alice += a[N-i] Alice a[N-i] a N-i N i {
				Bob += a[N-i];
			} Bob += a[N-i] Bob a[N-i] a N-i N i System.out.println(Alice - Bob) System.out.println 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 = 1; i < N+1; i++) {
			if(i % 2 == 1) {
				Alice += a[N-i];
			}else {
				Bob += a[N-i];
			}
		}
		System.out.println(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 = 1; i < N+1; i++) {
			if(i % 2 == 1) {
				Alice += a[N-i];
			}else {
				Bob += a[N-i];
			}
		}
		System.out.println(Alice - Bob);
	}

} Main
import java.util.Arrays;
import java.util.Scanner;

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 = 1; i < N+1; i++) {
			if(i % 2 == 1) {
				Alice += a[N-i];
			}else {
				Bob += a[N-i];
			}
		}
		System.out.println(Alice - Bob);
	}

}
