#include <bits/stdc++.h>
#ifdef _DEBUG
#include "debug.hpp"
#else
#define debug(...)
#endif
#define fastIO (cin.tie(0), cout.tie(0), ios::sync_with_stdio(false))
#define precise(i) fixed << setprecision(i)
using ill = int64_t;
using ull = uint64_t;
using namespace std;

void solve() {
  int n;
  cin >> n;

  vector<int> X;
  set<int> st;
  for (int i = 0, x; i < n; i++) {
    cin >> x;
    X.push_back(x);
    st.insert(x);
  }

  if (n != (int)st.size()) {
    cout << "NO" << '\n';
    return;
  }

  sort(X.begin(), X.end());

  int diff = X[0] - X[1];
  for (size_t i = 0; i < X.size() - 1; i++) {
    int cur = X[i] - X[i + 1];
    if (diff != cur) {
      cout << "NO" << '\n';
      return;
    }
  }

  cout << "YES" << '\n';
}

void wrapper() {
  int loop;
  cin >> loop;
  for (int i = 0; i < loop; i++) {
    auto start = chrono::steady_clock::now();
    cout << "[TEST " << i + 1 << "]\n";
    solve();
    auto end = chrono::steady_clock::now();
    chrono::duration<double> elapsed = end - start;
    cout << "[elapsed : " << elapsed.count() << "]" << '\n';
  }
}

int main() {
  fastIO;
#ifdef _DEBUG
  wrapper();
#else
  solve();
#endif
}