#include <iostream>
using namespace std;
const int MAX = 1000100;
int a[MAX];
int main()
{
	ios::sync_with_stdio(false);
	int n;
	cin >> n;
	for (int i = 0; i < n; i++)
	{
		int x;
		cin >> x;
		a[x]++;
	}
	int ans = 0;
	for (int i = 0; i < MAX - 1; i++)
	{
		a[i + 1] += a[i] / 2;
		a[i] %= 2;
		ans += a[i];
	}
	cout << ans << endl;
	return 0;
}