#include <bits/stdc++.h>
using namespace std;
int main() {
    int t;
    cin >> t;
    while (t--) {
        int n;
        cin >> n;
        vector<int> a(n);
        for (int i = 0; i < n; ++i) {
            cin >> a[i];
        }
        for (int size = n; size > 1; --size) {
            for (int i = 0; i < size - 1; ++i) {
                a[i] = a[i + 1] - a[i];
            }
            for (int j = 1; j < size - 1; ++j) {
                int key = a[j];
                int k = j - 1;
                while (k >= 0 && a[k] > key) {
                    a[k + 1] = a[k];
                    k--;
                }
                a[k + 1] = key;
            }
        }
        cout << a[0] << endl;
    }
    return 0;
}