import java.util.*;
 
public class Main {
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();
    Integer[] array = new Integer[n];
    for(int i = 0; i < n; i++) {
    	array[i] = sc.nextInt();
    }
    
    //降順にソート
    Arrays.sort(array, Collections.reverseOrder());
    
    int a = 0; //アリス
    int b = 0; //ボブ
    for(int i = 1; i <= n; i++) {
    	if(i % 2 == 1) {
        	a += array[i-1];
        } else {
        	b += array[i-1];
        }
    }
    System.out.println(a-b);
  }
} import java.util.*; util.* java public class Main {
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();
    Integer[] array = new Integer[n];
    for(int i = 0; i < n; i++) {
    	array[i] = sc.nextInt();
    }
    
    //降順にソート
    Arrays.sort(array, Collections.reverseOrder());
    
    int a = 0; //アリス
    int b = 0; //ボブ
    for(int i = 1; i <= n; i++) {
    	if(i % 2 == 1) {
        	a += array[i-1];
        } else {
        	b += array[i-1];
        }
    }
    System.out.println(a-b);
  }
} Main public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();
    Integer[] array = new Integer[n];
    for(int i = 0; i < n; i++) {
    	array[i] = sc.nextInt();
    }
    
    //降順にソート
    Arrays.sort(array, Collections.reverseOrder());
    
    int a = 0; //アリス
    int b = 0; //ボブ
    for(int i = 1; i <= n; i++) {
    	if(i % 2 == 1) {
        	a += array[i-1];
        } else {
        	b += array[i-1];
        }
    }
    System.out.println(a-b);
  } main {
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();
    Integer[] array = new Integer[n];
    for(int i = 0; i < n; i++) {
    	array[i] = sc.nextInt();
    }
    
    //降順にソート
    Arrays.sort(array, Collections.reverseOrder());
    
    int a = 0; //アリス
    int b = 0; //ボブ
    for(int i = 1; i <= n; i++) {
    	if(i % 2 == 1) {
        	a += array[i-1];
        } else {
        	b += array[i-1];
        }
    }
    System.out.println(a-b);
  } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc Integer[] array = new Integer[n]; array new Integer[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, Collections.reverseOrder()) Arrays.sort Arrays array Collections.reverseOrder() Collections.reverseOrder Collections int a = 0; a 0 int b = 0; b 0 for(int i = 1; i <= n; i++) {
    	if(i % 2 == 1) {
        	a += array[i-1];
        } else {
        	b += array[i-1];
        }
    } int i = 1; int i = 1; i 1 i <= n i n i++ i++ i {
    	if(i % 2 == 1) {
        	a += array[i-1];
        } else {
        	b += array[i-1];
        }
    } {
    	if(i % 2 == 1) {
        	a += array[i-1];
        } else {
        	b += array[i-1];
        }
    } if(i % 2 == 1) {
        	a += array[i-1];
        } else {
        	b += array[i-1];
        } i % 2 == 1 i % 2 i 2 1 {
        	a += array[i-1];
        } a += array[i-1] a array[i-1] array i-1 i 1 {
        	b += array[i-1];
        } b += array[i-1] b array[i-1] array i-1 i 1 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);
    int n = sc.nextInt();
    Integer[] array = new Integer[n];
    for(int i = 0; i < n; i++) {
    	array[i] = sc.nextInt();
    }
    
    //降順にソート
    Arrays.sort(array, Collections.reverseOrder());
    
    int a = 0; //アリス
    int b = 0; //ボブ
    for(int i = 1; i <= n; i++) {
    	if(i % 2 == 1) {
        	a += array[i-1];
        } else {
        	b += array[i-1];
        }
    }
    System.out.println(a-b);
  }
} public class Main {
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();
    Integer[] array = new Integer[n];
    for(int i = 0; i < n; i++) {
    	array[i] = sc.nextInt();
    }
    
    //降順にソート
    Arrays.sort(array, Collections.reverseOrder());
    
    int a = 0; //アリス
    int b = 0; //ボブ
    for(int i = 1; i <= n; i++) {
    	if(i % 2 == 1) {
        	a += array[i-1];
        } else {
        	b += array[i-1];
        }
    }
    System.out.println(a-b);
  }
} Main
import java.util.*;
 
public class Main {
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();
    Integer[] array = new Integer[n];
    for(int i = 0; i < n; i++) {
    	array[i] = sc.nextInt();
    }
    
    //降順にソート
    Arrays.sort(array, Collections.reverseOrder());
    
    int a = 0; //アリス
    int b = 0; //ボブ
    for(int i = 1; i <= n; i++) {
    	if(i % 2 == 1) {
        	a += array[i-1];
        } else {
        	b += array[i-1];
        }
    }
    System.out.println(a-b);
  }
}