import java.util.Arrays;
import java.util.Scanner;
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 x = 0;
    int y = 0;
    for(int i=0; i<N; i++) {
    	if(i%2==0) {
    		x += a[i];
    	}else {
    		y += a[i];
    	}
    	}
    System.out.println(Math.abs(x-y));
    }
}
/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz