#include <iostream>
#include <string>

using namespace std;

int main() {


	int n = 0;
	cin >> n;

	string s;
	cin >> s;

	//cout << n << endl;
	//cout << s << endl;
	int cnt =0;
	for(int i=0; i<n; ++i) {

		int x,o;
		x=o =0;

		for (int j = i; j<n; ++j) {
			if (s[j] == 'X') ++x;
			else ++o;

			//cout << "X " << x << " o " << o << " i " << i << " j " << j << " sj " << s[j] << endl;

			if ((o%4)==0 ) {
				int z=o/4 -1;
				if (z>0 && z*z == x) 
					++cnt;
			}
			if ((x%4)==0 ) {
				int z=x/4 -1;
				if (z>0 && z*z == o) 
					++cnt;
			}


		}
	}
	cout << cnt << endl;


	return 0;
}