#include <bits/stdc++.h>
using namespace std;
#define SC scanf
#define PF printf
#define ull unsigned long long
#define ld long double
#define F first
#define S second
#define pb push_back
#define sort_a(a) sort(a.begin(),a.end());
#define sort_d(a) sort(a.rbegin(),a.rend());
#define READ(f) freopen(f, "r", stdin)
#define WRITE(f) freopen(f, "w", stdout)
#define rev(s) reverse(s.begin(),s.end())
#define P(ok) cout << (ok ? "YES\n": "NO\n")
#define __Heart__ ios_base :: sync_with_stdio(false); cin.tie(NULL);
#define ll long long
typedef pair< ll , ll> PII;
void solve()
{
ll n , Roy = 0 , Hridoy = 0; cin >> n ; ll a[n] ;
for(auto &x : a) cin >> x ;
sort(a , a + n , greater <int> ()) ;
Roy = a[0] , Hridoy = a[1] ;
for(int i = 2 ; i < n ; i++){
if(a[i] < 0) break ;
if(i & 1){
Hridoy += a[i] ;
}
else Roy += a[i] ;
}
Roy -= Hridoy ;
cout << Roy << "\n" ;
}
int main()
{
__Heart__
int t ; cin >> t ; while(t--) solve() ;
}