#include <iostream>
#include <string>
#include <math.h>
#include <vector>

using namespace std;
int *file_vector;

int main()
{
    int file_length;
    string file;
    file_length = 0;
    int moznosti = 0;
    int nanic;
    cin >> nanic;
//    file = "XXOXXXXXXXX";//
    cin >> file;

    file_length = file.size();
    if(nanic != file_length){
        cout << 0;
        return 0;
    }


    vector<bool> v;




    for(int x = 0; x < file.size(); x++){
        char pismeno = file[x];
        if(pismeno == 'X'){
            v.push_back(1);
        } else {
            v.push_back(0);
        }

    }


    for(int strana_a = 3; strana_a <= sqrt(file_length); strana_a++){
//        cout << "strana: " << strana_a <<" \n";
        int celkovy_obsah = pow(strana_a,2);
        int vnutorny_obsah = pow(strana_a- 2, 2);
        for(int i = 0; i <= file.size()-pow(strana_a,2);i++){
//            cout << "zaciatok iteracie index: " << i <<" \n";
            int pocetx = 0;
            int poceto = 0;
            for(int x = i; x < i + pow(strana_a, 2); x++){
//                cout << "index: " << x <<" \n";
                if(v[x] == 0){
                    poceto++;
                } else {
                    pocetx++;
                }
            }
            if(poceto == vnutorny_obsah){
//                cout << "spravna\n";
                moznosti++;
            }

        }

    };
    cout << moznosti;


    return 0;
}