#include <iostream>
#include <vector>

int main() {
    int N;
    std::string s;

    std::cin >> N;
    s.reserve(N + 16);
    std::cin >> s;

    std::vector<int> count_x(N + 16);
    std::vector<int> count_o(N + 16);

    long long amount = 0;
    for (int i = 1; i <= N; ++i) {
        if (s[i - 1] == 'X') {
            count_x[i] = count_x[i - 1] + 1;
            count_o[i] = count_o[i - 1];
        } else {
            count_x[i] = count_x[i - 1];
            count_o[i] = count_o[i - 1] + 1;
        }

        for (int n = 3; n * n <= i; ++n) {
            int size = n * n;
            int x = count_x[i] - count_x[i - size];
            int o = count_o[i] - count_o[i - size];
            int exp1 = (n - 2) * (n - 2);
            int exp2 = size - exp1;

            if ((x == exp1 && o == exp2) || (x == exp2 && o == exp1))
                amount++;
        }

//        std::cout << amount << '\n';
//        std::cout << count_x[i] << ' ' << count_o[i] << '\n';

    }

    std::cout << amount << '\n';

    return 0;
}