#include <string>
#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;
typedef long long int ll;

#define x first
#define y second

int main() {

    ll n;
    cin >> n;

    string s;
    cin >> s;
    vector<ll> prefixX(1, 0);
    vector<ll> prefixO(1, 0);
    for (int i=0; i<n; i++){
        prefixX.push_back(prefixX.back() + (s[i] == 'X'));
        prefixO.push_back(prefixO.back() + (s[i] == 'O'));
    }
    ll result = 0;
    for (ll k = 1; (k + 2) * (k+2) <= n; k++) {
        ll length = (k + 2) * (k+2);
        for (ll i=0; i+length<=n; i++) {
            if (prefixX[i + length] - prefixX[i] == 4*k+4 && prefixO[i + length] - prefixO[i] == k*k) {
                result++;
            }
            else if (prefixX[i + length] - prefixX[i] == k*k && prefixO[i + length] - prefixO[i] == 4*k+4) {
                result++;
            }
        }
    }
    cout << result << '\n';
}