#include <bits/stdc++.h>
#define IOS ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define i64 long long
#define endl '\n'
#define lb(x) ((x) & (-x))
using namespace std;
const i64 mod = 1e18;
const int maxn = 1e3+10;
signed main()
{
    IOS;
    int t; cin >> t;
    while(t--)
    {
        int n; cin >> n;
        vector<i64> a(n+1);
        for(int i = 1; i <= n; ++i) cin >> a[i];
        sort(a.begin()+1,a.end());
        if(n == 1)
        {
            cout << a[1] << endl;
            continue;
        }
        i64 ans = 0;
        for(int i = 1; i <= n; ++i) ans += abs(a[i]);
        if(a[1] > 0)
        {
           if(n >= 4)  ans -= 2*a[1];
           else  ans -= a[1];
        }
        if(a[n] < 0) ans += a[1];
        cout << ans << endl;
    }
    return 0;
}