#include<bits/stdc++.h>
#define debug(x) cerr<<#x<<":"<<x<<"\n"
using namespace std;
using ll = long long;
using pii = pair <int,int>;
const int N = 1e6 + 5, MOD = 1e9 + 7;
int n;
ll a[N], s[N];
void solve()
{
    cin>>n;
    bool flag = 0;
    ll g = 0;
    for(int i=1;i<=n;i++)
    {
        cin>>a[i];
        g += abs(a[i]);
        if(a[i]<0) flag = 1;
        s[i] = s[i-1] + a[i];
    } 
    if(n==1) cout<<a[1]<<'\n';
    else if(n==2) cout<<max(a[2]-a[1],a[1]-a[2])<<'\n';
    else
    {
        if(flag) cout<<g<<'\n';
        else
        {
            ll ans = -1e18;
            for(int i=1;i<=n;i++)
            {
                if(i==1)
                {
                    ans = max(ans,a[n]-(a[1]-(s[n-1]-a[1])));
                }
                else
                {
                    ans = max(ans,a[i-1]-(a[i]-(s[n]-s[i])-s[i-2]));
                }
            }
            cout<<ans<<'\n';
        }
    }
}
int main(void)
{
    ios::sync_with_stdio(0);
    cin.tie(0), cout.tie(0);
    int T = 1;
    cin >> T;
    while(T--) solve();
    return 0;
}