import 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 sum = 0;
    int x = (n-1)%2;

    for (int i = n-1; i >= 0; i--) {
      if (i % 2 == x) {
        sum += a[i];
      } else {
        sum -= a[i];
      }
    }

    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();
    int[] a = new int[n];

    for (int i = 0; i < n; i++) {
      a[i] = sc.nextInt();
    }

    Arrays.sort(a);
    int sum = 0;
    int x = (n-1)%2;

    for (int i = n-1; i >= 0; i--) {
      if (i % 2 == x) {
        sum += a[i];
      } else {
        sum -= a[i];
      }
    }

    System.out.println(sum);
    
  }

} 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 sum = 0;
    int x = (n-1)%2;

    for (int i = n-1; i >= 0; i--) {
      if (i % 2 == x) {
        sum += a[i];
      } else {
        sum -= a[i];
      }
    }

    System.out.println(sum);
    
  } 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 sum = 0;
    int x = (n-1)%2;

    for (int i = n-1; i >= 0; i--) {
      if (i % 2 == x) {
        sum += a[i];
      } else {
        sum -= a[i];
      }
    }

    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 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 sum = 0; sum 0 int x = (n-1)%2; x (n-1)%2 (n-1) n 1 2 for (int i = n-1; i >= 0; i--) {
      if (i % 2 == x) {
        sum += a[i];
      } else {
        sum -= a[i];
      }
    } int i = n-1; int i = n-1; i n-1 n 1 i >= 0 i 0 i-- i-- i {
      if (i % 2 == x) {
        sum += a[i];
      } else {
        sum -= a[i];
      }
    } {
      if (i % 2 == x) {
        sum += a[i];
      } else {
        sum -= a[i];
      }
    } if (i % 2 == x) {
        sum += a[i];
      } else {
        sum -= a[i];
      } i % 2 == x i % 2 i 2 x {
        sum += a[i];
      } sum += a[i] sum a[i] a i {
        sum -= a[i];
      } sum -= a[i] sum a[i] a i 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();
    int[] a = new int[n];

    for (int i = 0; i < n; i++) {
      a[i] = sc.nextInt();
    }

    Arrays.sort(a);
    int sum = 0;
    int x = (n-1)%2;

    for (int i = n-1; i >= 0; i--) {
      if (i % 2 == x) {
        sum += a[i];
      } else {
        sum -= a[i];
      }
    }

    System.out.println(sum);
    
  }

} 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 sum = 0;
    int x = (n-1)%2;

    for (int i = n-1; i >= 0; i--) {
      if (i % 2 == x) {
        sum += a[i];
      } else {
        sum -= a[i];
      }
    }

    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();
    int[] a = new int[n];

    for (int i = 0; i < n; i++) {
      a[i] = sc.nextInt();
    }

    Arrays.sort(a);
    int sum = 0;
    int x = (n-1)%2;

    for (int i = n-1; i >= 0; i--) {
      if (i % 2 == x) {
        sum += a[i];
      } else {
        sum -= a[i];
      }
    }

    System.out.println(sum);
    
  }

}
