#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <climits>
#include <cfloat>
#include <map>
#include <utility>
#include <set>
#include <iostream>
#include <memory>
#include <string>
#include <vector>
#include <algorithm>
#include <functional>
#include <sstream>
#include <complex>
#include <stack>
#include <queue>
#include <iomanip>
#include <array>
#include <numeric>
#include <regex>
#include <bitset>
#include <deque>

using namespace std;
typedef long long ll;
typedef pair<int, int> p_ii;

const int INF = 1e9;
const double PI = acos(-1.0);
const ll MOD = 1e9 + 7;



int main() {
    int d;
    cin>>d;
    
    vector<char>a(30);
    for (int i = 0; i < 30; i++) {
        if(i>=14)a[i]='x';
        else cin>>a[i];
    }

    int res=d;

    for (int i = 0; i < 30; i++) {
        vector<char>t(30);
        for (int j = 0; j < 30; j++) {
            t[j]=a[j];
        }
        for (int j = 0; j < d; j++) {
           if(i+j>=30)continue;
           t[i+j]='o'; 
        }
        int tres=0;
        for (int j = 0; j < 30; j++) {
            if(t[j]=='o')tres++;
            else{
                res=max(res,tres);
                tres=0;
            }
        }
        res=max(res,tres);
    }
    cout<<res<<endl;

    return 0;
}