import java.io.*;

import java.util.Scanner;

public class Practice {

public static void main(String[] args) {

Scanner sc = new Scanner(System.in);

int n = sc.nextInt();

int[] arr = new int[n];

for (int i = 0; i < n; i++) {

arr[i] = sc.nextInt();

}

// Sort the array in descending order

for (int i = 0; i < n; i++) {

for (int j = i + 1; j < n; j++) {

if (arr[i] < arr[j]) {

int temp = arr[i];

arr[i] = arr[j];

arr[j] = temp;

}

}

}

int sum = 0;

for (int i = 0; i < n / 2; i++) {

sum = sum + (arr[i] - arr[n - i - 1]);

}

System.out.println(sum);

}

}