#include <bits/stdc++.h>
using namespace std;
mt19937 rnd(chrono::steady_clock::now().time_since_epoch().count());
long long powmod(long long a, long long b, long long mod) {
  if (b == 0 || a == 1) {
    if (mod == 1)
      return 0;
    else
      return 1;
  }
  if (b % 2 == 0) {
    long long k = powmod(a, b / 2, mod);
    return (k * k) % mod;
  } else {
    long long k = powmod(a, b / 2, mod);
    return ((k * k) % mod * a) % mod;
  }
}
long long gcd(long long a, long long b) {
  if (a == 0) return b;
  if (b == 0) return a;
  if (a > b)
    return gcd(a % b, b);
  else
    return gcd(b % a, a);
}
long long prime(long long p) {
  for (long long i = 2; i * i <= p; i++) {
    if (p % i == 0 && i < p) return i;
  }
  return 1;
}
long long inv(long long a, long long mod) { return powmod(a, mod - 2, mod); }
long long random_modul() {
  uniform_int_distribution<long long> u1(1e9, 2e9);
  long long pepega = u1(rnd);
  while (prime(pepega) != 1) pepega = u1(rnd);
  return pepega;
}
void solve() {
  long long a;
  cin >> a;
  long long m[a];
  map<long long, long long> ch;
  for (long long i = 0; i < a; i++) {
    cin >> m[i];
    ch[m[i]]++;
  }
  vector<long long> lol;
  for (auto i : ch) {
    lol.push_back(i.second);
  }
  sort(lol.begin(), lol.end());
  long long ans[a + 1];
  long long max1 = 0;
  for (long long i = 0; i <= a; i++) ans[i] = 0;
  for (long long i = 0; i < lol.size(); i++) {
    for (long long j = lol[i]; j >= 0; j--) {
      ans[j] = max(ans[j], j);
      if (j % 2 == 0) ans[j] = max(ans[j], ans[j / 2] + j);
    }
  }
  for (long long i = 0; i <= a; i++) max1 = max(max1, ans[i]);
  cout << max1;
  return;
}
signed main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  long long tututu;
  tututu = 1;
  for (long long qwerty = 0; qwerty < tututu; qwerty++) solve();
  return 0;
}
