/*
    JAI JAGANNATH!
*/
//@Author : zanj0

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;

template <class T>
using ordered_set = __gnu_pbds::tree<T, __gnu_pbds::null_type, less<T>, __gnu_pbds::rb_tree_tag, __gnu_pbds::tree_order_statistics_node_update>;


#define ff first
#define ss second
#define pb push_back
#define MOD 1000000007
#define inf 1e18
#define ps(x, y) fixed << setprecision(y) << x
#define w(x)  \
    int x;    \
    cin >> x; \
    while (x--)
#define endl "\n"
#define timetaken cerr << "Time : " << 1000 * (long double)clock() / (long double)CLOCKS_PER_SEC << "ms\n"

typedef long long int lli;

void zanj0()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
#ifdef LOCAL
    freopen("input.txt", "r", stdin);
#endif
}
void Solve()
{
    lli ret = 0;
    lli n;
    cin >> n;
    vector<lli> v(n);
    for (int i = 0; i < n; i++)
    {
        cin >> v[i];
    }
    sort(v.rbegin(), v.rend());
    ret = v[0] - v[1];
    for (int i = 2; i < n; i++)
    {
        if (v[i] < 0)
            break;
        if (i % 2 == 0)
            ret += v[i];
        else
            ret -= v[i];
    }
    cout << ret << endl;
}
int32_t main()
{
    zanj0();
    w(t) Solve();
    timetaken;
    return 0;
}