#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <stack>
#include <queue>
#include <list>
#include <set>
#include <map>
#include <numeric>
#include <regex>
#include <tuple>
#include<iomanip>
using namespace std;

typedef long long ll;
typedef pair<int, int> P;
#define MOD 1000000007 // 10^9 + 7
#define INF 1000000000 // 10^9
#define LLINF 1LL<<60

bool hol[14];

int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);

	int D; cin >> D;
	for (int i = 0; i < 14; i++) {
		char tmp;
		cin >> tmp;
		if (tmp == 'o') hol[i] = true;
	}

	int ans = D;

	for (int i = 0; i <= 14 - D; i++) {
		// i日目から有休を使う

		bool tmphol[14];
		for (int j = 0; j < 14; j++) {
			tmphol[j] = hol[j];
			if (i <= j && j <= i + D - 1) tmphol[j] = true;
		}

		vector<int> V;
		int len = 0;
		for (int j = 0; j < 14; j++) {
			if (tmphol[j]) len++;
			else {
				V.push_back(len);
				len = 0;
			}
		}
		V.push_back(len);
		sort(V.begin(), V.end(), greater<int>());
		ans = max(ans, V[0]);
	}

	cout << ans << endl;

	return 0;
}