#include <bits/stdc++.h>
using namespace std;
void fun() {}
long long int md = 998244353;
long long int __gcd(long long int a, long long int b) {
  if (b == 0) return a;
  return __gcd(b, a % b);
}
long long int poww(long long int a, long long int b, long long int md) {
  if (b < 0) return 0;
  if (a == 0) return 0;
  long long int res = 1;
  while (b) {
    if (b & 1) {
      res = (1ll * res * a) % md;
    }
    a = (1ll * a * a) % md;
    b >>= 1;
  }
  return res;
}
long long int poww(long long int a, long long int b) {
  if (b < 0) return 0;
  if (a == 0) return 0;
  long long int res = 1;
  while (b) {
    if (b & 1) {
      res = (1ll * res * a);
    }
    a = (1ll * a * a);
    b >>= 1;
  }
  return res;
}
void ainp(long long int arr[], long long int n) {
  for (long long int i = 1; i <= n; i++) cin >> arr[i];
}
void disp(long long int arr[], long long int n) {
  for (long long int i = 1; i <= n; i++) cout << arr[i] << " ";
  cout << "\n";
}
void dispv(vector<long long int> &v) {
  for (long long int i = 0; i < v.size(); i++) cout << v[i] << " ";
  cout << "\n";
}
long long int divide(long long int a, long long int b, long long int md) {
  long long int rr = a * (poww(b, md - 2, md));
  rr %= md;
  return rr;
}
const long long int size = 2e5 + 2;
long long int arr[size];
long long int n;
map<long long int, long long int> mapp;
set<pair<long long int, long long int> > sett;
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  fun();
  cin >> n;
  for (long long int i = 1; i <= n; i++) {
    cin >> arr[i];
    mapp[arr[i]]++;
  }
  for (auto i : mapp) sett.insert(make_pair(i.second, i.first));
  long long int ans = 0;
  for (long long int i = 1; i <= n; i++) {
    vector<pair<long long int, long long int> > vec;
    long long int cnt = i;
    long long int tempans = 0;
    while (sett.lower_bound(make_pair(cnt, 0ll)) != sett.end()) {
      auto itr = sett.lower_bound(make_pair(cnt, 0ll));
      tempans += cnt;
      cnt = cnt * 2;
      vec.push_back(*itr);
      sett.erase(itr);
    }
    for (auto itr : vec) sett.insert(itr);
    ans = max(ans, tempans);
  }
  cout << ans << "\n";
  return 0;
}
