#include<sstream>
#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<string>
#include<vector>
#include<set>
#include<map>
#include<queue>
#include<numeric>
#include<functional>
#include<algorithm>
using namespace std;
#define INF (1<<29)
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define all(v) v.begin(),v.end()
#define uniq(v) v.erase(unique(all(v)),v.end())
#define indexOf(v,x) (find(all(v),x)-v.begin())




int main(){
	char c[14];
	int ans=0,len=0,d;
	vector<pair<int,int> > v;

	cin>>d;
	rep(i,14)cin>>c[i];
	rep(i,14){
		if(c[i]=='o')len++;
		else if(len){
			v.push_back(make_pair(i-len,i-1));
			len=0;
		}
		ans=max(ans,len);
	}
	if(len)v.push_back(make_pair(14-len,14-1));
	rep(i,(int)v.size()-1){
		if(v[i+1].first-v[i].second-1<=d){
			ans=max(ans,v[i+1].second-v[i].first+1);
		}else{
			ans=max(ans,max(v[i].second-v[i].first,v[i+1].second-v[i+1].first)+1+d);
		}
	}
	if(v.size()){
		ans=max(ans,v[0].second-v[0].first+1+min(v[0].first,d));
		ans=max(ans,v.back().second-v.back().first+1+min(13-v.back().second,d));
	}
	cout<<ans<<endl;
	return 0;
}