#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int main()
{
    int n;
    cin >> n;

    vector<long long> A(n);
    for (int i = 0; i < n; i++)
    {
        cin >> A[i];
    }

    sort(A.begin(), A.end(), [](long long a, long long b)
         { return abs(a) > abs(b); });

    long long X = 0, Y = 0;

    for (int i = 0; i < n; i++)
    {
        if (i % 2 == 0)
        {
            X += A[i]; 
        }
        else
        {
            Y += A[i]; 
        }
    }

    cout << X - Y << endl;

    return 0;
}