#pragma GCC optimize("Ofast,unroll-loops")
#include <bits/stdc++.h>
using namespace std;
int n;
char arr[200005];
long long psum[200005], res;
int main(){
    int tiles;
    scanf("%d", &n);
    for(int i = 1; i <= n; ++i)scanf(" %c", &arr[i]);
    for(int i = 1; i <= n; ++i){
        psum[i]=(arr[i]=='X')+psum[i-1];
    }
    for(int k = 1; (k+2)*(k+2) <= n;++k){
        for(int j = 0; j+(k+2)*(k+2)<=n;++j){
            long long cnt = psum[j+(k+2)*(k+2)] - psum[j];
            //for(int l=j;l<j+(k+2)*(k+2);++l)
            //    cnt+=arr[l]=='X';
            //printf("%d %d %d\n", cnt, psum[j+(k+2)*(k+2)], psum[j]);
            if(cnt == k*k || cnt == 2*(2*k+2))++res;
        }
    }  
    cout << res << "\n";
    return 0;
}