#include <bits/stdc++.h>

using namespace std;

typedef vector<int> vi;
typedef pair<int, int> pii;
typedef long long ll;

#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define REP(i,n)  FOR(i,0,n)
#define INF 1e9

int main(){
    const int N =14;
    char days[N];
    int D;
    cin >> D ;
    for(int i =0;i<N;i++)
        cin >> days[i] ;

    int l = 0;
    int ans = 0;
    for(l=0;l<N;l++){
        int to_holiday = D;
        int count = 0;
        for(int i=l;i<N;i++){
            if(days[i] == 'x')
                to_holiday--;
            if(days[i] == 'o' && to_holiday!=D)
                to_holiday=0;
            if(to_holiday<0)
                break;
            count++;
        }
        if(to_holiday)
            count += to_holiday;
            
        ans = max(ans,count);
    }
    cout << ans << endl;
    return 0;

}