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

int d, ans;

void solve(int cnt, vector<bool> tf) {
	cnt++;

	int cnt2=0;
	for (int j = 0; j < 14; j++) {
		if (!tf[j]) {	//cout << cnt << endl;
			//cout << j << endl;
			vector<bool>tf2;
			tf2 = tf;
			tf2[j] = true;
			if (cnt == d) {
				for (int k = 0; k < 14; k++) {
					if (tf2[k]) cnt2++;
					else {
						//cout << cnt2 << endl;
						ans = max(cnt2, ans);
						cnt2 = 0;
					}
				}
				ans = max(cnt2, ans);
				//cout << ans << endl;
				cnt2 = 0;
			}
			else {
				solve(cnt, tf2);
			}
		}
	}
}

int main()
{
	int cnt = 0;
	vector<bool> tf;
	tf.resize(14);

	cin >> d;

	for (int i = 0; i < 14; i++) {
		char c;
		cin >> c;
		if (c == 'o') tf[i] = true;
		else tf[i] = false;
	}

	solve(0, tf);

	cout << ans << endl;

    return 0;
}