//Yukicoder
//Q204　ＧＷ２

//二次元可変配列
//vector <vector <int>> mass;
//vector <vector <int>> memo;

//#include "stdafx.h"
#include <iostream>
#include <vector>
#include <list>//list
#include <set> //tree
#include <map> //連想配列
#include <unordered_set> //hash
#include <unordered_map> //hash
#include <algorithm>
#include <iomanip>
#include <cstring>

using namespace std;
typedef unsigned long long LL;


#define START (0)
#define RIGHT (1)
#define UP    (2)
#define LEFT  (3)
#define DOWN  (4)



#define DATA_MAX (1000000)

char a[60];
int  memo[60];
char _a[60];

int main()
{
	int N;
	int limit = 0;

	cin >> N;

	int j = 0;
	int i = 0;

	//前の2週間
	for (i = 0; i < 14; i++)
	{
		a[i] = 'x';
		memo[j] = i;
		j++;
	}

	for (i = 14; i < 28; i++)
	{
		cin >> a[i];
		if (a[i] == 'x')
		{
			memo[j] = i;
			j++;
		}
	}
	

	//後の2週間
	for (i = 28; i < 42; i++)
	{
		a[i] = 'x';
	}
	memo[j] = 28;

	memcpy(_a,a, 60);

	
	limit = j+1;
	j = 0;
	int max = 0;
	int ans = 0;

	while(1)
	{
		int flag = 0;
		for (int k=0;k<N;k++)
		{
			if (flag && a[memo[j]+k] == 'o')
				break;
			a[memo[j]+k] = 'o';
			flag = 1;	
		}

		/*
		//debug print
		for (i = 0; i < 42; i++)
		{
			cout <<a[i]<<",";

		}
		cout << endl;
	*/

		ans = 0;
		for (int k = 0; k < 42; k++)
		{
			if (a[k] == 'o')
				ans++;
			else
				ans = 0;

			if (ans > max)
				max = ans;
		}
		
		memcpy(a, _a, 60);
		
		j++;

		if (limit == j)
			break;

	}


	cout <<  max << endl;
	
	//getchar();
	return 0;
}