#include <bits/stdc++.h>
using namespace std;
void solve() {
    int n;
    cin >> n;
    vector<long long>v(n);
    for(int i = 0; i < n; i++){
        cin >> v[i];
    }
    sort(v.rbegin(),v.rend());
    vector<long long>ans;
    long long sum = v[0] - v[1];
    if(n == 2){
        cout << sum << "\n";
    }
    else{
        for(int i = 2; i < n; i++){
        if(i%2 == 0){
            if(v[i] > 0){
                sum += v[i];
            }
            else{
                cout << sum << "\n";
                return;
            }
        }
        else{
            if(v[i] > 0){
                sum -= v[i];
            }
            else{
                cout << sum << "\n";
                return;
            }
        }  
       
    }

    cout << sum << "\n";

    }

}
int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
    int t;
    cin >> t;
    while(t--) {
        solve();
    }
}