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

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 bob = 0, alice = 0;
      	boolean flag = true;
      	int i = n-1;
      	while(i >= 0){
          if(flag){
            alice += a[i];
          	flag = !flag;
          }else{
            bob +=a[i];
            flag = !flag;
          }
    		i--;
    	}
      	System.out.println(alice - bob);
      	
	}
} import java.util.Scanner; Scanner java.util import java.util.Arrays; Arrays java.util import java.util.ArrayList; ArrayList java.util 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 bob = 0, alice = 0;
      	boolean flag = true;
      	int i = n-1;
      	while(i >= 0){
          if(flag){
            alice += a[i];
          	flag = !flag;
          }else{
            bob +=a[i];
            flag = !flag;
          }
    		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 bob = 0, alice = 0;
      	boolean flag = true;
      	int i = n-1;
      	while(i >= 0){
          if(flag){
            alice += a[i];
          	flag = !flag;
          }else{
            bob +=a[i];
            flag = !flag;
          }
    		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 bob = 0, alice = 0;
      	boolean flag = true;
      	int i = n-1;
      	while(i >= 0){
          if(flag){
            alice += a[i];
          	flag = !flag;
          }else{
            bob +=a[i];
            flag = !flag;
          }
    		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] a i sc.nextInt() sc.nextInt sc Arrays.sort(a) Arrays.sort Arrays a int bob = 0 bob 0 alice = 0; alice 0 boolean flag = true; flag true int i = n-1; i n-1 n 1 while(i >= 0){
          if(flag){
            alice += a[i];
          	flag = !flag;
          }else{
            bob +=a[i];
            flag = !flag;
          }
    		i--;
    	} i >= 0 i 0 {
          if(flag){
            alice += a[i];
          	flag = !flag;
          }else{
            bob +=a[i];
            flag = !flag;
          }
    		i--;
    	} if(flag){
            alice += a[i];
          	flag = !flag;
          }else{
            bob +=a[i];
            flag = !flag;
          } flag {
            alice += a[i];
          	flag = !flag;
          } alice += a[i] alice a[i] a i flag = !flag flag !flag flag {
            bob +=a[i];
            flag = !flag;
          } bob +=a[i] bob a[i] a i flag = !flag flag !flag flag i-- i System.out.println(alice - bob) System.out.println System.out System System.out alice - bob alice bob String[] args args
import java.util.Scanner;
import java.util.Arrays;
import java.util.ArrayList;

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 bob = 0, alice = 0;
      	boolean flag = true;
      	int i = n-1;
      	while(i >= 0){
          if(flag){
            alice += a[i];
          	flag = !flag;
          }else{
            bob +=a[i];
            flag = !flag;
          }
    		i--;
    	}
      	System.out.println(alice - bob);
      	
	}
}