#include <bits/stdc++.h>

using ll = long long;
using namespace std;


char sequence[200001];

int main(){
    ll n;
    cin >> n;

    for(int i = 0; i < n; i++){
        char c;
        cin >> c;
        sequence[i] = c;
    }

    ll result = 0;


    for(int i = 3; i*i <= n; i++){
        //scitaj prvych tychto panv
        ll blue = 0;
        ll red = 0;
        for(int j = 0; j < i*i; j++){
            if(sequence[j] == 'X')
                blue++;
            else
                red++;
        }
        ll j = 0;
        while(j + i*i <= n){
            if(blue == pow(i - 2, 2) && red == 2*(2*i - 2) ||
               red == pow(i - 2, 2) && blue == 2*(2*i - 2))
                result++;

            if(sequence[j] == 'X')
                blue--;
            else
                red--;
            if(sequence[j + i*i] == 'X')
                blue++;
            else
                red++;
            j++;
        }
    }

    cout << result << endl;




}