#include <iostream>
#include <algorithm>
#include <vector>
#include <string>
#include <utility>
#include <cmath>
#include <iomanip>
#include <map>
#include <set>
#include <bitset>

using namespace std;


int main()
{
	/*for (long long i = 1; i <= 50000; i++)
	{
		if (i*i + 4 * i + 4 <= 200000)
			cout << i << " " << i*i << " " << i*4+4 << endl;
	}*/
	ios_base::sync_with_stdio(0);
	int grb;
	cin >> grb;
	string vstup(grb, '\0');
	cin >> vstup;
	long long res = 0;
	for (long long i = 1; i <= 445; i++)
	{
		long long xcnt = 0;
		long long ocnt = 0;
		long long bin_length = (i * i + (i * 4 + 4));
		bool prec = false;
		for (long long j = 0; j < bin_length; j++)
		{
			if (vstup.size() <= j)
			{
				prec = true;
				break;
			}
				
			switch (vstup[j])
			{
			case 'X':
				xcnt++;
				break;
			case 'O':
				ocnt++;
				break;
			}
		}
		if (prec)
			break;

		if (i * i == xcnt || i * i == ocnt)
		{
			res++;
		}

		for (long long j = bin_length; j < vstup.size(); j++)
		{
			switch (vstup[j])
			{
			case 'X':
				xcnt++;
				break;
			case 'O':
				ocnt++;
				break;
			}
			switch (vstup[j - bin_length])
			{
			case 'X':
				xcnt--;
				break;
			case 'O':
				ocnt--;
				break;
			}
			if (i * i == xcnt || i * i == ocnt)
			{
				res++;
			}
		}
	}

	cout << res << "\n";
	return 0;
}