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

void solve() {
    int n; cin >> n;
    int a[n]; for (auto& x : a) cin >> x;
    sort(a, a+n, greater<>());
    long long S = 0;
    for (int i = 0; i < n; i++) {
        if (a[i] < 0) break;
        S += i & 1 ? -a[i] : a[i];
    }
    cout << S << "\n";
}

signed main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int t; cin >> t; while (t--)
        solve();
}