#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;

using isize = size_t;
using i32 = int;
using u32 = unsigned int;
using i64 = long long;
using u64 = unsigned long long;
using i128 = __int128_t;
using u128 = __uint128_t;
using f64 = long double;
using p2 = pair<i64, i64>;
using el = tuple<i64, i64, i64>;
using mint = atcoder::modint998244353;

void _main();
int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  cout << fixed << setprecision(18);
  _main();
}

i64 pow(i64 x, i64 n) {
  i64 res = 1;
  i64 t = x;
  while (n > 0) {
    if (n & 1) res *= t;
    t *= t;
    n >>= 1;
  }
  return res;
}
i64 pow(i64 x, i64 n, i64 m) {
  i64 res = 1;
  i64 t = x % m;
  while (n > 0) {
    if (n & 1) res = res * t % m;
    t = t * t % m;
    n >>= 1;
  }
  return res;
}

void _main() {
  i64 n;
  cin >> n;
  vector<i64> h(n);
  vector<i64> cnt(n + 70, 0);
  for (i64 i = 0; i < n; i++) {
    cin >> h[i];
    i64 x = 0;
    while (h[i] > 0) {
      x++;
      h[i] >>= 1;
    }
    cnt[x]++;
  }
  i64 mx = 0;
  for (i64 i = 0; i < cnt.size(); i++) {
    if (cnt[i] > 0) mx = i;
    if (cnt[i] > 2) {
      cnt[i + 1] += cnt[i] - 1;
      cnt[i] = 1;
    }
  }
  cout << mx << "\n";
}