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;
		int check = 0;
		
		for(int i = N - 1; i > -1; i--) {
			if(check == 0) {
				alice += a[i];
				check = 1;
			} else {
				bob += a[i];
				check = 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[] a = new int[N];
		
		for(int i = 0; i < N; i++) {
			a[i] = sc.nextInt();
		}
		
		Arrays.sort(a);
		
		int alice = 0;
		int bob = 0;
		int check = 0;
		
		for(int i = N - 1; i > -1; i--) {
			if(check == 0) {
				alice += a[i];
				check = 1;
			} else {
				bob += a[i];
				check = 0;
			}
		}
		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;
		int check = 0;
		
		for(int i = N - 1; i > -1; i--) {
			if(check == 0) {
				alice += a[i];
				check = 1;
			} else {
				bob += a[i];
				check = 0;
			}
		}
		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;
		int check = 0;
		
		for(int i = N - 1; i > -1; i--) {
			if(check == 0) {
				alice += a[i];
				check = 1;
			} else {
				bob += a[i];
				check = 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[] 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 int check = 0; check 0 for(int i = N - 1; i > -1; i--) {
			if(check == 0) {
				alice += a[i];
				check = 1;
			} else {
				bob += a[i];
				check = 0;
			}
		} int i = N - 1; int i = N - 1; i N - 1 N 1 i > -1 i -1 1 i-- i-- i {
			if(check == 0) {
				alice += a[i];
				check = 1;
			} else {
				bob += a[i];
				check = 0;
			}
		} {
			if(check == 0) {
				alice += a[i];
				check = 1;
			} else {
				bob += a[i];
				check = 0;
			}
		} if(check == 0) {
				alice += a[i];
				check = 1;
			} else {
				bob += a[i];
				check = 0;
			} check == 0 check 0 {
				alice += a[i];
				check = 1;
			} alice += a[i] alice a[i] a i check = 1 check 1 {
				bob += a[i];
				check = 0;
			} bob += a[i] bob a[i] a i check = 0 check 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[] a = new int[N];
		
		for(int i = 0; i < N; i++) {
			a[i] = sc.nextInt();
		}
		
		Arrays.sort(a);
		
		int alice = 0;
		int bob = 0;
		int check = 0;
		
		for(int i = N - 1; i > -1; i--) {
			if(check == 0) {
				alice += a[i];
				check = 1;
			} else {
				bob += a[i];
				check = 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[] a = new int[N];
		
		for(int i = 0; i < N; i++) {
			a[i] = sc.nextInt();
		}
		
		Arrays.sort(a);
		
		int alice = 0;
		int bob = 0;
		int check = 0;
		
		for(int i = N - 1; i > -1; i--) {
			if(check == 0) {
				alice += a[i];
				check = 1;
			} else {
				bob += a[i];
				check = 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[] a = new int[N];
		
		for(int i = 0; i < N; i++) {
			a[i] = sc.nextInt();
		}
		
		Arrays.sort(a);
		
		int alice = 0;
		int bob = 0;
		int check = 0;
		
		for(int i = N - 1; i > -1; i--) {
			if(check == 0) {
				alice += a[i];
				check = 1;
			} else {
				bob += a[i];
				check = 0;
			}
		}
		System.out.println(alice - bob);
	}
}
