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[] array = new int[N];
		for(int i=0;i<N;i++) {
			array[i] = sc.nextInt();
		}
		Arrays.sort(array);
		int alice=0,bob=0,flag=0;
		for(int i=N-1;i>=0;i--) {
			if(flag==0) {
				alice+=array[i];
				flag=1;
			}else {
				bob+=array[i];
				flag=0;
			}
		}
		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[] array = new int[N];
		for(int i=0;i<N;i++) {
			array[i] = sc.nextInt();
		}
		Arrays.sort(array);
		int alice=0,bob=0,flag=0;
		for(int i=N-1;i>=0;i--) {
			if(flag==0) {
				alice+=array[i];
				flag=1;
			}else {
				bob+=array[i];
				flag=0;
			}
		}
		System.out.println(alice-bob);
	}
} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		int[] array = new int[N];
		for(int i=0;i<N;i++) {
			array[i] = sc.nextInt();
		}
		Arrays.sort(array);
		int alice=0,bob=0,flag=0;
		for(int i=N-1;i>=0;i--) {
			if(flag==0) {
				alice+=array[i];
				flag=1;
			}else {
				bob+=array[i];
				flag=0;
			}
		}
		System.out.println(alice-bob);
	} main {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		int[] array = new int[N];
		for(int i=0;i<N;i++) {
			array[i] = sc.nextInt();
		}
		Arrays.sort(array);
		int alice=0,bob=0,flag=0;
		for(int i=N-1;i>=0;i--) {
			if(flag==0) {
				alice+=array[i];
				flag=1;
			}else {
				bob+=array[i];
				flag=0;
			}
		}
		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[] array = new int[N]; array new int[N] N for(int i=0;i<N;i++) {
			array[i] = sc.nextInt();
		} int i=0; int i=0; i 0 i<N i N i++ i++ i {
			array[i] = sc.nextInt();
		} {
			array[i] = sc.nextInt();
		} array[i] = sc.nextInt() array[i] array i sc.nextInt() sc.nextInt sc Arrays.sort(array) Arrays.sort Arrays array int alice=0 alice 0 bob=0 bob 0 flag=0; flag 0 for(int i=N-1;i>=0;i--) {
			if(flag==0) {
				alice+=array[i];
				flag=1;
			}else {
				bob+=array[i];
				flag=0;
			}
		} int i=N-1; int i=N-1; i N-1 N 1 i>=0 i 0 i-- i-- i {
			if(flag==0) {
				alice+=array[i];
				flag=1;
			}else {
				bob+=array[i];
				flag=0;
			}
		} {
			if(flag==0) {
				alice+=array[i];
				flag=1;
			}else {
				bob+=array[i];
				flag=0;
			}
		} if(flag==0) {
				alice+=array[i];
				flag=1;
			}else {
				bob+=array[i];
				flag=0;
			} flag==0 flag 0 {
				alice+=array[i];
				flag=1;
			} alice+=array[i] alice array[i] array i flag=1 flag 1 {
				bob+=array[i];
				flag=0;
			} bob+=array[i] bob array[i] array i flag=0 flag 0 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[] array = new int[N];
		for(int i=0;i<N;i++) {
			array[i] = sc.nextInt();
		}
		Arrays.sort(array);
		int alice=0,bob=0,flag=0;
		for(int i=N-1;i>=0;i--) {
			if(flag==0) {
				alice+=array[i];
				flag=1;
			}else {
				bob+=array[i];
				flag=0;
			}
		}
		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[] array = new int[N];
		for(int i=0;i<N;i++) {
			array[i] = sc.nextInt();
		}
		Arrays.sort(array);
		int alice=0,bob=0,flag=0;
		for(int i=N-1;i>=0;i--) {
			if(flag==0) {
				alice+=array[i];
				flag=1;
			}else {
				bob+=array[i];
				flag=0;
			}
		}
		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[] array = new int[N];
		for(int i=0;i<N;i++) {
			array[i] = sc.nextInt();
		}
		Arrays.sort(array);
		int alice=0,bob=0,flag=0;
		for(int i=N-1;i>=0;i--) {
			if(flag==0) {
				alice+=array[i];
				flag=1;
			}else {
				bob+=array[i];
				flag=0;
			}
		}
		System.out.println(alice-bob);
	}
}
