#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int t;
  cin >> t;
  while (t--) {
    int n;
    cin >> n;
    long long a;
    long long mx = -99999999999;
    long long val = 0;
    for (int i = 0; i < n; i++) {
      cin >> a;
      mx = max(mx, a);
      val = max(val, mx - a);
    }
    int i = 0;
    while (val > (1LL << i) - 1) i++;
    cout << i << "\n";
  }
}
