#include <iostream>
#include <vector>
using namespace std;
int main(){
	int D;
	cin >> D;
	vector<char> C(42, 'x');
	for (int i = 14; i < 21; i++){
		cin >> C[i];
	}
	for (int i = 21; i < 28; i++){
		cin >> C[i];
	}
	int ans = 0;
	for (int i = 0; i < 42; i++){
		vector<char> C2 = C;
		for (int j = i; j < min(i + D, 42); j++){
			if (C[j] == 'o'){
				break;
			}
			C2[j] = 'o';
		}
		int mx = 0;
		int con = 0;
		for (int j = 0; j < 42; j++){
			if (C2[j] == 'o'){
				con++;
				mx = max(mx, con);
			} else {
				con = 0;
			}
		}
		ans = max(ans, mx);
	}
	cout << ans << endl;
}