#include <bits/stdc++.h>
using namespace std;

#define ll long long
#define int long long
#define all(x) (x).begin(), (x).end()
#define f(i, n) for (int i = 0; i < n; i++)
#define trace(x) cerr << #x << ": " << x << '\n'
int32_t main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    int t;
    cin >> t;
    while (t--)
    {
        int n;
        cin >> n;
        vector<int> v(n);
        f(i, n) cin >> v[i];
        sort(all(v));
        int s = v[n - 1] - v[n - 2];
        if (n == 2 or v[n - 3] < 0)
            cout << s << endl;
        else
        {
            int res = s;
            s += v[n - 3];
            if (n > 4)
                s -= v[n - 4];
            res = min(res, s);
            cout << res << endl;
        }
    }
}