#include <bits/stdc++.h>

using namespace std;

int main()
{
    int n, i, j;
    string s;
    cin >> n;
    cin >> s;
    int maxA = (int)sqrt(n), in, out, tot = 0;
    char C = 'O';
    for (i = 3; i <= maxA; i++) {
        int in = out = 0, m = i * i;
        for (j = 0; j < m; j++) {
            if (s[j] == C) in++;
            else out++;
        }
        for (j = 0; j < n - m; j++) {
            if (in == (i - 2) * (i - 2) && in + out == m) tot++;
            if (out == (i-2)*(i-2) && in + out == m) tot++;
            if (s[j] == C) in--;
            else out--;
            if (s[j + m] == C) in++;
            else out++;
        }
        if (in == (i - 2) * (i - 2) && in + out == m) tot++;
        if (out == (i-2)*(i-2) && in + out == m) tot++;
    }
    cout << tot << endl;
}