#include <bits/stdc++.h>
using namespace std;
int main() {
  long long n;
  cin.sync_with_stdio(false);
  cout.sync_with_stdio(false);
  cin >> n;
  vector<long long> q(1000100, 0);
  for (long long i = 0; i < n; i++) {
    long long t;
    cin >> t;
    q[t]++;
  }
  long long ans = 0;
  for (long long i = 0; (i < 1000100 - 1); ++i) {
    if (q[i] % 2 == 1) ans++;
    q[i + 1] += q[i] / 2;
  }
  cout << ans;
  return 0;
}
