#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  int q;
  cin >> q;
  while (q--) {
    int n, c = 1;
    cin >> n;
    vector<int> x(n, 0);
    for (int i = 0; i < n; i++) {
      cin >> x[i];
    }
    vector<int> t;
    sort(x.begin(), x.end());
    t.push_back(x[0]);
    for (int i = 1; i < n; i++) {
      bool f = false;
      for (int j = 0; j < t.size(); j++) {
        if (t[j] != 0) {
          if (x[i] - t[j] > 1) {
            f = true;
            t[j] = x[i];
            break;
          }
        }
      }
      if (!f) {
        t.push_back(x[i]);
        c++;
      }
    }
    cout << c << endl;
    x.clear();
    t.clear();
  }
  return 0;
}
