import java.util.*;
import java.lang.*;


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 alice = 0;
        int bob = 0;
        if (n % 2 == 0) {
            for (int i = 1; i < n; i += 2) {
                alice += a[i];
            }
            for (int i = 0; i < n - 1; i += 2) {
                bob += a[i];
            }
        } else {
            for (int i = 0; i < n; i += 2) {
                alice += a[i];
            }
            for (int i = 1; i < n - 1; i += 2) {
                bob += a[i];
            }
        }
        System.out.println(alice - bob);
    }
} import java.util.*; util.* java import java.lang.*; lang.* 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 alice = 0;
        int bob = 0;
        if (n % 2 == 0) {
            for (int i = 1; i < n; i += 2) {
                alice += a[i];
            }
            for (int i = 0; i < n - 1; i += 2) {
                bob += a[i];
            }
        } else {
            for (int i = 0; i < n; i += 2) {
                alice += a[i];
            }
            for (int i = 1; i < n - 1; i += 2) {
                bob += a[i];
            }
        }
        System.out.println(alice - bob);
    }
} 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 alice = 0;
        int bob = 0;
        if (n % 2 == 0) {
            for (int i = 1; i < n; i += 2) {
                alice += a[i];
            }
            for (int i = 0; i < n - 1; i += 2) {
                bob += a[i];
            }
        } else {
            for (int i = 0; i < n; i += 2) {
                alice += a[i];
            }
            for (int i = 1; i < n - 1; i += 2) {
                bob += a[i];
            }
        }
        System.out.println(alice - bob);
    } 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 alice = 0;
        int bob = 0;
        if (n % 2 == 0) {
            for (int i = 1; i < n; i += 2) {
                alice += a[i];
            }
            for (int i = 0; i < n - 1; i += 2) {
                bob += a[i];
            }
        } else {
            for (int i = 0; i < n; i += 2) {
                alice += a[i];
            }
            for (int i = 1; i < n - 1; i += 2) {
                bob += a[i];
            }
        }
        System.out.println(alice - bob);
    } 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 alice = 0; alice 0 int bob = 0; bob 0 if (n % 2 == 0) {
            for (int i = 1; i < n; i += 2) {
                alice += a[i];
            }
            for (int i = 0; i < n - 1; i += 2) {
                bob += a[i];
            }
        } else {
            for (int i = 0; i < n; i += 2) {
                alice += a[i];
            }
            for (int i = 1; i < n - 1; i += 2) {
                bob += a[i];
            }
        } n % 2 == 0 n % 2 n 2 0 {
            for (int i = 1; i < n; i += 2) {
                alice += a[i];
            }
            for (int i = 0; i < n - 1; i += 2) {
                bob += a[i];
            }
        } for (int i = 1; i < n; i += 2) {
                alice += a[i];
            } int i = 1; int i = 1; i 1 i < n i n i += 2 i += 2 i 2 {
                alice += a[i];
            } {
                alice += a[i];
            } alice += a[i] alice a[i] a i for (int i = 0; i < n - 1; i += 2) {
                bob += a[i];
            } int i = 0; int i = 0; i 0 i < n - 1 i n - 1 n 1 i += 2 i += 2 i 2 {
                bob += a[i];
            } {
                bob += a[i];
            } bob += a[i] bob a[i] a i {
            for (int i = 0; i < n; i += 2) {
                alice += a[i];
            }
            for (int i = 1; i < n - 1; i += 2) {
                bob += a[i];
            }
        } for (int i = 0; i < n; i += 2) {
                alice += a[i];
            } int i = 0; int i = 0; i 0 i < n i n i += 2 i += 2 i 2 {
                alice += a[i];
            } {
                alice += a[i];
            } alice += a[i] alice a[i] a i for (int i = 1; i < n - 1; i += 2) {
                bob += a[i];
            } int i = 1; int i = 1; i 1 i < n - 1 i n - 1 n 1 i += 2 i += 2 i 2 {
                bob += a[i];
            } {
                bob += a[i];
            } bob += a[i] bob a[i] a i System.out.println(alice - bob) System.out.println System.out System System.out alice - bob alice bob 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 alice = 0;
        int bob = 0;
        if (n % 2 == 0) {
            for (int i = 1; i < n; i += 2) {
                alice += a[i];
            }
            for (int i = 0; i < n - 1; i += 2) {
                bob += a[i];
            }
        } else {
            for (int i = 0; i < n; i += 2) {
                alice += a[i];
            }
            for (int i = 1; i < n - 1; i += 2) {
                bob += a[i];
            }
        }
        System.out.println(alice - bob);
    }
} 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 alice = 0;
        int bob = 0;
        if (n % 2 == 0) {
            for (int i = 1; i < n; i += 2) {
                alice += a[i];
            }
            for (int i = 0; i < n - 1; i += 2) {
                bob += a[i];
            }
        } else {
            for (int i = 0; i < n; i += 2) {
                alice += a[i];
            }
            for (int i = 1; i < n - 1; i += 2) {
                bob += a[i];
            }
        }
        System.out.println(alice - bob);
    }
} Main
import java.util.*;
import java.lang.*;


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 alice = 0;
        int bob = 0;
        if (n % 2 == 0) {
            for (int i = 1; i < n; i += 2) {
                alice += a[i];
            }
            for (int i = 0; i < n - 1; i += 2) {
                bob += a[i];
            }
        } else {
            for (int i = 0; i < n; i += 2) {
                alice += a[i];
            }
            for (int i = 1; i < n - 1; i += 2) {
                bob += a[i];
            }
        }
        System.out.println(alice - bob);
    }
}
