#include <iostream>
#include <vector>


using namespace std;

int main (){
    int n; cin >> n;
    string s; cin >> s;
    int slen = s.size();

    vector<int> patios;

    int curr = 3;

    while (true) {

        if (curr * curr <= slen){
            patios.push_back(curr);
        }
        else {
            break;
            }
        curr += 1;

    }

    int result = 0;

    for (int p : patios) {
        int si = 0;
        int ei = p*p - 1;
        int cx = 0;
        int co = 0;
        for (int i = si; i <= ei; ++i){
            if(s[i]=='O'){
                co += 1;
            } else {
                cx += 1;
            }
        }
        int inner = (p - 2) * (p - 2);
        while (ei < slen){
            
            if (inner == co || inner == cx){
                result += 1;
            }
            
            if (s[si] == 'O'){
                co -= 1;
            } else {
                cx -= 1;
            }
            si++;
            if (ei + 1 == slen){
                break;
            }
            ei++;
            if (s[ei]=='O'){
                co+=1;
            } else {
                cx++;
            }

        }
    }


    cout << result << endl;

    return 0;
}