#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
using namespace std;

int d,ans;

int main()
{
	int cnt = 0;
	vector<bool> tf;
	tf.resize(42);

	cin >> d;

	for (int i = 14; i < 28; i++) {
		char c;
		cin >> c;
		if (c == 'o') tf[i] = true;
	}

	for (int i = 0; i < 29; i++) {
		if (!tf[i]) {
			vector<bool>tf2;
			tf2 = tf;
			for (int j = 0; j < d; j++) {
				if(!tf2[i+j]) tf2[i+j] = true;
				else break;
			}
			cnt = 0;
			for (int k = 0; k < 42; k++) {
				if (tf2[k]) cnt++;
				else {
					ans = max(ans, cnt);
					cnt=0;
				}
			}
			ans = max(ans, cnt);
		}
	}

	cout << ans << endl;

    return 0;
}