import java.util.*;

public class Main {
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();    
    ArrayList<Integer> list = new ArrayList<>();
    int sum = 0;
    
    for(int i=0; i<N; i++) {
      list.add(sc.nextInt());
    }
    Collections.sort(list, Collections.reverseOrder());
    for(int j=0; j<list.size(); j++) {
      if(j % 2 == 0) {
        sum += list.get(j);
      } else {
        sum -= list.get(j);
      }
    }
    System.out.println(sum);
  }
} import java.util.*; util.* java public class Main {
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();    
    ArrayList<Integer> list = new ArrayList<>();
    int sum = 0;
    
    for(int i=0; i<N; i++) {
      list.add(sc.nextInt());
    }
    Collections.sort(list, Collections.reverseOrder());
    for(int j=0; j<list.size(); j++) {
      if(j % 2 == 0) {
        sum += list.get(j);
      } else {
        sum -= list.get(j);
      }
    }
    System.out.println(sum);
  }
} Main public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();    
    ArrayList<Integer> list = new ArrayList<>();
    int sum = 0;
    
    for(int i=0; i<N; i++) {
      list.add(sc.nextInt());
    }
    Collections.sort(list, Collections.reverseOrder());
    for(int j=0; j<list.size(); j++) {
      if(j % 2 == 0) {
        sum += list.get(j);
      } else {
        sum -= list.get(j);
      }
    }
    System.out.println(sum);
  } main {
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();    
    ArrayList<Integer> list = new ArrayList<>();
    int sum = 0;
    
    for(int i=0; i<N; i++) {
      list.add(sc.nextInt());
    }
    Collections.sort(list, Collections.reverseOrder());
    for(int j=0; j<list.size(); j++) {
      if(j % 2 == 0) {
        sum += list.get(j);
      } else {
        sum -= list.get(j);
      }
    }
    System.out.println(sum);
  } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int N = sc.nextInt(); N sc.nextInt() sc.nextInt sc ArrayList<Integer> list = new ArrayList<>(); list new ArrayList<>() int sum = 0; sum 0 for(int i=0; i<N; i++) {
      list.add(sc.nextInt());
    } int i=0; int i=0; i 0 i<N i N i++ i++ i {
      list.add(sc.nextInt());
    } {
      list.add(sc.nextInt());
    } list.add(sc.nextInt()) list.add list sc.nextInt() sc.nextInt sc Collections.sort(list, Collections.reverseOrder()) Collections.sort Collections list Collections.reverseOrder() Collections.reverseOrder Collections for(int j=0; j<list.size(); j++) {
      if(j % 2 == 0) {
        sum += list.get(j);
      } else {
        sum -= list.get(j);
      }
    } int j=0; int j=0; j 0 j<list.size() j list.size() list.size list j++ j++ j {
      if(j % 2 == 0) {
        sum += list.get(j);
      } else {
        sum -= list.get(j);
      }
    } {
      if(j % 2 == 0) {
        sum += list.get(j);
      } else {
        sum -= list.get(j);
      }
    } if(j % 2 == 0) {
        sum += list.get(j);
      } else {
        sum -= list.get(j);
      } j % 2 == 0 j % 2 j 2 0 {
        sum += list.get(j);
      } sum += list.get(j) sum list.get(j) list.get list j {
        sum -= list.get(j);
      } sum -= list.get(j) sum list.get(j) list.get list j System.out.println(sum) System.out.println System.out System System.out sum String[] args args public class Main {
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();    
    ArrayList<Integer> list = new ArrayList<>();
    int sum = 0;
    
    for(int i=0; i<N; i++) {
      list.add(sc.nextInt());
    }
    Collections.sort(list, Collections.reverseOrder());
    for(int j=0; j<list.size(); j++) {
      if(j % 2 == 0) {
        sum += list.get(j);
      } else {
        sum -= list.get(j);
      }
    }
    System.out.println(sum);
  }
} public class Main {
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();    
    ArrayList<Integer> list = new ArrayList<>();
    int sum = 0;
    
    for(int i=0; i<N; i++) {
      list.add(sc.nextInt());
    }
    Collections.sort(list, Collections.reverseOrder());
    for(int j=0; j<list.size(); j++) {
      if(j % 2 == 0) {
        sum += list.get(j);
      } else {
        sum -= list.get(j);
      }
    }
    System.out.println(sum);
  }
} Main
import java.util.*;

public class Main {
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();    
    ArrayList<Integer> list = new ArrayList<>();
    int sum = 0;
    
    for(int i=0; i<N; i++) {
      list.add(sc.nextInt());
    }
    Collections.sort(list, Collections.reverseOrder());
    for(int j=0; j<list.size(); j++) {
      if(j % 2 == 0) {
        sum += list.get(j);
      } else {
        sum -= list.get(j);
      }
    }
    System.out.println(sum);
  }
}
