# include <bits/stdc++.h>

using namespace std;

void solve ()
{
    int n, k, val;
    vector <int> vec;
    cin >> n;
    int start = 0, nzind = 0;
    for (int i = 0; i < n; i++)
    {
        cin >> val;
        vec.push_back (val);
        if (val == 0)
            nzind++;
    }

    while (nzind < n - 1)
    {
        if (nzind != 0)
            vec[nzind - 1] = vec[nzind];
        for (int i = nzind; i < n - 1; i++)
            vec[i] = vec[i + 1] - vec[i];
        if (nzind > 0)
            nzind--;
        n--;
        sort (vec.begin() + nzind, vec.begin() + n);
        while (vec[nzind] == 0)
            nzind++;
    }

    cout << vec[n - 1] << '\n';

}

int main ()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    int t;
    cin >> t;
    while (t--)
        solve();
}