#include <bits/stdc++.h>

using namespace std;

using ll = long long;
using pii = pair<int, int>;
using ld = long double;

template <typename T>
int sz(T &x) {
  return (int)(x.size());
}

int power(int x, int y, int mod) {
  if (y == 0) {
    return 1;
  }
  int z = power(x, y >> 1, mod);
  z = z * 1ll * z % mod;
  if (y & 1) {
    z = z * 1ll * x % mod;
  }
  return z;
}

const int mod = 998244353;
const int inf = 1000000007;
const ll linf = inf * 1ll * inf * 8;

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

void solve() {
  int n;
  cin >> n;
  vector<ll> a(n);
  for (int i = 0; i < n; ++i) {
    cin >> a[i];
  }
  int cntZero = 0;
  for (int step = 1; step < n; ++step) {
    sort(a.begin(), a.end());
    vector<ll> b;
    if (cntZero > 0) {
      cntZero--;
      b.push_back(a[0]);
    }
    for (int i = 1; i < sz(a); ++i) {
      if (a[i] == a[i - 1]) {
        cntZero++;
      } else {
        b.push_back(a[i] - a[i - 1]);
      }
    }
    a = b;
  }
  if (cntZero) {
    cout << "0\n";
  } else {
    cout << a[0] << "\n";
  }
}


int main() {

  #ifndef LOCAL58
    ios_base :: sync_with_stdio(false);
    cin.tie(nullptr);
  #endif


  int t = 1;
  cin >> t;
  while (t--) {
    solve();
  }

  return 0;
}