import java.util.*;
import static java.lang.Math.*;

public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		
		// 入力
		int n = sc.nextInt();
		int[] a = new int[n];
		for(int i = 0; i < n; i++){
		    a[i] = sc.nextInt();
		}
		Arrays.sort(a);
		
		// 計算
		int result = 0;
		for(int i = n-1; i >= 0; i--){
		    if(i%2 != n%2){
		        result += a[i];
		    }else{
		        result -= a[i];
		    }
		}
		
		// 出力
		System.out.println(result);
		
	}
}

 import java.util.*; util.* java import static java.lang.Math.*; import static java.lang.Math.*; import static java.lang.Math.*; public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		
		// 入力
		int n = sc.nextInt();
		int[] a = new int[n];
		for(int i = 0; i < n; i++){
		    a[i] = sc.nextInt();
		}
		Arrays.sort(a);
		
		// 計算
		int result = 0;
		for(int i = n-1; i >= 0; i--){
		    if(i%2 != n%2){
		        result += a[i];
		    }else{
		        result -= a[i];
		    }
		}
		
		// 出力
		System.out.println(result);
		
	}
} Main public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		
		// 入力
		int n = sc.nextInt();
		int[] a = new int[n];
		for(int i = 0; i < n; i++){
		    a[i] = sc.nextInt();
		}
		Arrays.sort(a);
		
		// 計算
		int result = 0;
		for(int i = n-1; i >= 0; i--){
		    if(i%2 != n%2){
		        result += a[i];
		    }else{
		        result -= a[i];
		    }
		}
		
		// 出力
		System.out.println(result);
		
	} main {
		Scanner sc = new Scanner(System.in);
		
		// 入力
		int n = sc.nextInt();
		int[] a = new int[n];
		for(int i = 0; i < n; i++){
		    a[i] = sc.nextInt();
		}
		Arrays.sort(a);
		
		// 計算
		int result = 0;
		for(int i = n-1; i >= 0; i--){
		    if(i%2 != n%2){
		        result += a[i];
		    }else{
		        result -= a[i];
		    }
		}
		
		// 出力
		System.out.println(result);
		
	} 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 result = 0; result 0 for(int i = n-1; i >= 0; i--){
		    if(i%2 != n%2){
		        result += a[i];
		    }else{
		        result -= 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 != n%2){
		        result += a[i];
		    }else{
		        result -= a[i];
		    }
		} {
		    if(i%2 != n%2){
		        result += a[i];
		    }else{
		        result -= a[i];
		    }
		} if(i%2 != n%2){
		        result += a[i];
		    }else{
		        result -= a[i];
		    } i%2 != n%2 i%2 i 2 n%2 n 2 {
		        result += a[i];
		    } result += a[i] result a[i] a i {
		        result -= a[i];
		    } result -= a[i] result a[i] a i System.out.println(result) System.out.println System.out System System.out result String[] args args public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		
		// 入力
		int n = sc.nextInt();
		int[] a = new int[n];
		for(int i = 0; i < n; i++){
		    a[i] = sc.nextInt();
		}
		Arrays.sort(a);
		
		// 計算
		int result = 0;
		for(int i = n-1; i >= 0; i--){
		    if(i%2 != n%2){
		        result += a[i];
		    }else{
		        result -= a[i];
		    }
		}
		
		// 出力
		System.out.println(result);
		
	}
} public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		
		// 入力
		int n = sc.nextInt();
		int[] a = new int[n];
		for(int i = 0; i < n; i++){
		    a[i] = sc.nextInt();
		}
		Arrays.sort(a);
		
		// 計算
		int result = 0;
		for(int i = n-1; i >= 0; i--){
		    if(i%2 != n%2){
		        result += a[i];
		    }else{
		        result -= a[i];
		    }
		}
		
		// 出力
		System.out.println(result);
		
	}
} Main
import java.util.*;
import static java.lang.Math.*;

public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		
		// 入力
		int n = sc.nextInt();
		int[] a = new int[n];
		for(int i = 0; i < n; i++){
		    a[i] = sc.nextInt();
		}
		Arrays.sort(a);
		
		// 計算
		int result = 0;
		for(int i = n-1; i >= 0; i--){
		    if(i%2 != n%2){
		        result += a[i];
		    }else{
		        result -= a[i];
		    }
		}
		
		// 出力
		System.out.println(result);
		
	}
}


