import std.stdio, std.string, std.conv;
import std.range, std.algorithm, std.array;

void main() {
    int n = readln.chomp.to!int;
    auto a = readln.split.to!(int[]);

    a.sort!"a > b"();

    int res;

    foreach (i ; 0 .. n) {
        res += (-1)^^(i) * a[i];
    }

    writeln(res);
}




void scan(T...)(ref T args) {
    import std.stdio : readln;
    import std.algorithm : splitter;
    import std.conv : to;
    import std.range.primitives;

    auto line = readln().splitter();
    foreach (ref arg; args) {
        arg = line.front.to!(typeof(arg));
        line.popFront();
    }
    assert(line.empty);
}



void fillAll(R, T)(ref R arr, T value) {
    static if (is(typeof(arr[] = value))) {
        arr[] = value;
    }
    else {
        foreach (ref e; arr) {
            fillAll(e, value);
        }
    }
}

struct Queue(T) {
    private {
        size_t cap, head, tail;
        T[] data;
    }

    this (size_t n) in {
        assert(n > 0, "The capacity of a queue must be a positive integer.");
    } body {
        cap = n + 1;
        data = new T[](cap);
    }

    void clear() {
        head = tail = 0;
    }

    bool empty() {
        return head == tail;
    }

    bool full() {
        return head == (tail + 1) % cap;
    }

    size_t length() {
        return head <= tail ? tail - head : cap - head + tail;
    }

    T front() in {
        assert(!empty, "The queue is empty.");
    } body {
        return data[head];
    }

    void removeFront() in {
        assert(!empty, "The queue is empty.");
    } body {
        (++head) %= cap;
    }

    alias popFront = removeFront;

    void insertBack(T x) in {
        assert(!full, "The queue is full.");
    } body {
        data[tail++] = x;
        tail %= cap;
    }

    alias insert = insertBack;

    T[] array() {
        return head <= tail ? data[head .. tail].dup : data[head .. $] ~ data[0 .. tail];
    }

    string toString() {
        import std.format : format;

        if (head <= tail) {
            return format("[%(%s, %)]", data[head .. tail]);
        }
        else {
            return format("[%(%s, %)", data[head .. $]) ~ format(", %(%s, %)]", data[0 .. tail]);
        }
    }
}