#include<bits/stdc++.h>
namespace {
#pragma GCC diagnostic ignored "-Wunused-function"
#include<atcoder/all>
#pragma GCC diagnostic warning "-Wunused-function"
using namespace std;
using namespace atcoder;
#define rep(i,n) for(int i = 0; i < (int)(n); i++)
#define rrep(i,n) for(int i = (int)(n) - 1; i >= 0; i--)
#define all(x) begin(x), end(x)
#define rall(x) rbegin(x), rend(x)
template<class T> bool chmax(T& a, const T& b) { if (a < b) { a = b; return true; } else return false; }
template<class T> bool chmin(T& a, const T& b) { if (b < a) { a = b; return true; } else return false; }
using ll = long long;
using P = pair<int,int>;
using VI = vector<int>;
using VVI = vector<VI>;
using VL = vector<ll>;
using VVL = vector<VL>;

} int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n;
  cin >> n;
  VL h(n);
  rep(i, n) cin >> h[i];
  int l = 0, r = n + 65;
  constexpr long long INF = 1002003004005006007;
  while (r - l > 1) {
    int c = (l + r) / 2;
    VL atc(c);
    atc[0] = 1;
    rep(i, c - 1) {
      atc[i+1] = atc[i] * 2;
      chmin(atc[i+1], INF);
    }
    priority_queue<ll> q;
    rep(i, n) q.emplace(h[i]);
    for (ll v : atc | views::reverse) {
      if (q.empty()) break;
      ll hp = q.top(); q.pop();
      hp -= v;
      if (hp > 0) q.emplace(hp);
    }
    (q.empty() ? r : l) = c;
  }
  cout << r << '\n';
}