#include <cstdio>
#include <iostream>
#include <vector>
#include <map>
#include <set>
#include <string>
#include <cstring>
#include <sstream>
#include <algorithm>
#include <functional>
#include <queue>
#include <stack>
#include <cmath>
#include <iomanip>
#include <list>
#include <bitset>
using namespace std;
inline int toInt(string s) { int v; istringstream sin(s); sin >> v; return v; }
template<class T> inline string toString(T x) { ostringstream sout; sout << x; return sout.str(); }
template<class T> inline T sqr(T x) { return x*x; }
typedef pair<int, int> P;
typedef long long ll;
typedef unsigned long long ull;

#define For(i,a,b)	for(int (i) = (a);i < (b);(i)++)
#define rep(i,n)	For(i,0,n)
#define clr(a)		memset((a), 0 ,sizeof(a))
#define mclr(a)		memset((a), -1 ,sizeof(a))
#define all(a)		(a).begin(),(a).end()
#define rall(a)		(a).rbegin(), (a).rend()
#define sz(a)		(sizeof(a))
#define Fill(a,v)	fill((int*)a,(int*)(a+(sz(a)/sz(*(a)))),v)
#define fi first
#define se second
bool cheak(int x, int y, int xMax, int yMax){ return x >= 0 && y >= 0 && xMax > x && yMax > y; }
const int dx[4] = { -1, 0, 1, 0 }, dy[4] = { 0, 1, 0, -1 };
const int mod = 1000000007;
const int INF = 1e9;

int main()
{
	int D = 0;
	int ans = 0; 
	cin >> D;

	char c[257]; 
	rep(i, 256)c[i] = 'x';
	rep(i,14)cin >> c[i+50];


	rep(k, 256){
		bool f[257]; clr(f);
		for (int j = k; j < 256 && j < k + D; j++){
			if (c[j] == 'x'){
				f[j] = true;
			}
			int count = 0;
			rep(i, 256){
				if (c[i] == 'o' || f[i])count++;
				else count = 0;

				ans = max(count, ans);
			}
			if (c[j] == 'o')break;
		}
	}

	cout << ans << endl;

	return 0;
}