#include <iostream>
#include <vector>
#include <cmath>

using namespace std;

int main() {

    int nmbTiles;
    string input;

    cin >> nmbTiles;
    cin >> input;

    vector<int> xCount;
    vector<int> oCount;
    int xSum = 0;
    int oSum = 0;
    xCount.push_back(xSum);
    oCount.push_back(oSum);
    for (int i = 0; i < input.length(); i++) {
        if (input[i] == 'X') {
            xSum++;
        } else {
            oSum++;
        }
        xCount.push_back(xSum);
        oCount.push_back(oSum);
    }

    int out = 0;
    for (int right = 0; right <= input.length(); right++) {
        for (int left = 0; left < right; left++) {
            int xInside = xCount[right] - xCount[left];
            int oInside = oCount[right] - oCount[left];

            int n = (int)sqrt(oInside);
            if (n * n != oInside || oInside == 0) {
                continue; // skip if O is not n^2
            }

            int xExpected = 4 * n + 4;
            int oExpected = n * n;
            if (xInside < xExpected || oInside < oExpected) {
                break;
            }

            if (xInside == 4 * n + 4) {
                out++;
            }
        }
    }
    cout << out << endl;
    return 0;
}