import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = Integer.parseInt(sc.next());
        int[] a = new int[n];
        for(int i=0; i<n; i++) {
            a[i] = Integer.parseInt(sc.next());
        }
        Arrays.sort(a);
        int asum = 0;
        int bsum = 0;
        for(int i=n-1; i>=0; i--) {
            if((n-1) % 2 == 0) {
                if(i % 2 == 0) asum += a[i];
                else bsum += a[i];
            }else {
                if(i % 2 == 1) asum += a[i];
                else bsum += a[i];
            }
        }
        
        System.out.println(asum - bsum);
    }
} import java.util.*; util.* java public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = Integer.parseInt(sc.next());
        int[] a = new int[n];
        for(int i=0; i<n; i++) {
            a[i] = Integer.parseInt(sc.next());
        }
        Arrays.sort(a);
        int asum = 0;
        int bsum = 0;
        for(int i=n-1; i>=0; i--) {
            if((n-1) % 2 == 0) {
                if(i % 2 == 0) asum += a[i];
                else bsum += a[i];
            }else {
                if(i % 2 == 1) asum += a[i];
                else bsum += a[i];
            }
        }
        
        System.out.println(asum - bsum);
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = Integer.parseInt(sc.next());
        int[] a = new int[n];
        for(int i=0; i<n; i++) {
            a[i] = Integer.parseInt(sc.next());
        }
        Arrays.sort(a);
        int asum = 0;
        int bsum = 0;
        for(int i=n-1; i>=0; i--) {
            if((n-1) % 2 == 0) {
                if(i % 2 == 0) asum += a[i];
                else bsum += a[i];
            }else {
                if(i % 2 == 1) asum += a[i];
                else bsum += a[i];
            }
        }
        
        System.out.println(asum - bsum);
    } main {
        Scanner sc = new Scanner(System.in);
        int n = Integer.parseInt(sc.next());
        int[] a = new int[n];
        for(int i=0; i<n; i++) {
            a[i] = Integer.parseInt(sc.next());
        }
        Arrays.sort(a);
        int asum = 0;
        int bsum = 0;
        for(int i=n-1; i>=0; i--) {
            if((n-1) % 2 == 0) {
                if(i % 2 == 0) asum += a[i];
                else bsum += a[i];
            }else {
                if(i % 2 == 1) asum += a[i];
                else bsum += a[i];
            }
        }
        
        System.out.println(asum - bsum);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n = Integer.parseInt(sc.next()); n Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc int[] a = new int[n]; a new int[n] n for(int i=0; i<n; i++) {
            a[i] = Integer.parseInt(sc.next());
        } int i=0; int i=0; i 0 i<n i n i++ i++ i {
            a[i] = Integer.parseInt(sc.next());
        } {
            a[i] = Integer.parseInt(sc.next());
        } a[i] = Integer.parseInt(sc.next()) a[i] a i Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc Arrays.sort(a) Arrays.sort Arrays a int asum = 0; asum 0 int bsum = 0; bsum 0 for(int i=n-1; i>=0; i--) {
            if((n-1) % 2 == 0) {
                if(i % 2 == 0) asum += a[i];
                else bsum += a[i];
            }else {
                if(i % 2 == 1) asum += a[i];
                else bsum += a[i];
            }
        } int i=n-1; int i=n-1; i n-1 n 1 i>=0 i 0 i-- i-- i {
            if((n-1) % 2 == 0) {
                if(i % 2 == 0) asum += a[i];
                else bsum += a[i];
            }else {
                if(i % 2 == 1) asum += a[i];
                else bsum += a[i];
            }
        } {
            if((n-1) % 2 == 0) {
                if(i % 2 == 0) asum += a[i];
                else bsum += a[i];
            }else {
                if(i % 2 == 1) asum += a[i];
                else bsum += a[i];
            }
        } if((n-1) % 2 == 0) {
                if(i % 2 == 0) asum += a[i];
                else bsum += a[i];
            }else {
                if(i % 2 == 1) asum += a[i];
                else bsum += a[i];
            } (n-1) % 2 == 0 (n-1) % 2 (n-1) n 1 2 0 {
                if(i % 2 == 0) asum += a[i];
                else bsum += a[i];
            } if(i % 2 == 0) asum += a[i];
                else bsum += a[i]; i % 2 == 0 i % 2 i 2 0 asum += a[i] asum a[i] a i bsum += a[i] bsum a[i] a i {
                if(i % 2 == 1) asum += a[i];
                else bsum += a[i];
            } if(i % 2 == 1) asum += a[i];
                else bsum += a[i]; i % 2 == 1 i % 2 i 2 1 asum += a[i] asum a[i] a i bsum += a[i] bsum a[i] a i System.out.println(asum - bsum) System.out.println System.out System System.out asum - bsum asum bsum String[] args args public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = Integer.parseInt(sc.next());
        int[] a = new int[n];
        for(int i=0; i<n; i++) {
            a[i] = Integer.parseInt(sc.next());
        }
        Arrays.sort(a);
        int asum = 0;
        int bsum = 0;
        for(int i=n-1; i>=0; i--) {
            if((n-1) % 2 == 0) {
                if(i % 2 == 0) asum += a[i];
                else bsum += a[i];
            }else {
                if(i % 2 == 1) asum += a[i];
                else bsum += a[i];
            }
        }
        
        System.out.println(asum - bsum);
    }
} public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = Integer.parseInt(sc.next());
        int[] a = new int[n];
        for(int i=0; i<n; i++) {
            a[i] = Integer.parseInt(sc.next());
        }
        Arrays.sort(a);
        int asum = 0;
        int bsum = 0;
        for(int i=n-1; i>=0; i--) {
            if((n-1) % 2 == 0) {
                if(i % 2 == 0) asum += a[i];
                else bsum += a[i];
            }else {
                if(i % 2 == 1) asum += a[i];
                else bsum += a[i];
            }
        }
        
        System.out.println(asum - bsum);
    }
} Main
import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = Integer.parseInt(sc.next());
        int[] a = new int[n];
        for(int i=0; i<n; i++) {
            a[i] = Integer.parseInt(sc.next());
        }
        Arrays.sort(a);
        int asum = 0;
        int bsum = 0;
        for(int i=n-1; i>=0; i--) {
            if((n-1) % 2 == 0) {
                if(i % 2 == 0) asum += a[i];
                else bsum += a[i];
            }else {
                if(i % 2 == 1) asum += a[i];
                else bsum += a[i];
            }
        }
        
        System.out.println(asum - bsum);
    }
}
