#include <bits/stdc++.h>
using namespace std;
using ll = long long;

void solve();

int main() {
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);
    int tc; cin >> tc;
    for (int tt = 0; tt < tc; tt++) solve();
    return 0;
}

void solve() {
    int n; cin >> n;
    vector<int> a(n);
    for (int &x : a) cin >> x;
    sort(a.begin(), a.end(), greater<int>());
    ll ans = a[0] - a[1];
    for (int i = 2; i < n; i++) {
        if (a[i] > 0) {
            if (i & 1) ans -= a[i];
            else ans += a[i];
        }
    }
    cout << ans << "\n";
}