#include "bits/stdc++.h"
using namespace std;
#define ll long long int
#define rep(i,n) for( int i = 0; i < n; i++ )
#define rrep(i,n) for( int i = n; i >= 0; i-- )
#define REP(i,s,t) for( int i = s; i <= t; i++ )
#define RREP(i,s,t) for( int i = s; i >= t; i-- )
#define dump(x)  cerr << #x << " = " << (x) << endl;
#define INF 2000000000
#define mod 1000000007
#define INF2 1000000000000000000


int main(void)
{
    cin.tie(0);
    ios::sync_with_stdio(false);
	int D; cin >> D;
	int cal[42] = {};
	rep(i, 14) {
		char c; cin >> c;
		if (c == 'o') {
			cal[14 + i] = 1;
		}
		else {
			cal[14 + i] = 0;
		}
	}
	int ans = 0;
	rep(i, 42 - D + 1) {
		int tmp[42] = {};
		rep(j, 42) tmp[j] = cal[j];
		REP(j, i, i + D - 1) {
			if (tmp[j] == 0)
				tmp[j] = 1;
			else break;
		}
		int tmp1 = 0;
		rep(j, 42) {
			if (tmp[j]) tmp1++;
			else tmp1 = 0;
			ans = max(ans, tmp1);
		}
	}
	cout << ans << endl;

    return 0;
}