#include <bits/stdc++.h>
using namespace std;
#define int long long
#define stoi stoll
using ll=long long;
using vi=vector<int>;
using pii=pair<int,int>;
#define ALL(c) begin(c),end(c)
#define RALL(c) rbegin(c),rend(c)
#define ITR(i,b,e) for(auto i=(b);i!=(e);++i)
#define FORE(x,c) for(auto &x:c)
#define REPF(i,a,n) for(int i=a,i##len=(int)(n);i<i##len;++i)
#define REP(i,n) REPF(i,0,n)
#define REPR(i,n) for(int i=(int)(n);i>=0;--i)
#define SZ(c) ((int)c.size())
#define CONTAIN(c,x) (c.find(x)!=end(c))
#define OUTOFRANGE(y,x,h,w) (y<0||x<0||y>=h||x>=w)
#define dump(...)
const signed INF_=1001001001; const ll INF=1001001001001001001LL;
const int DX[9]={0,1,0,-1,1,1,-1,-1,0},DY[9]={-1,0,1,0,-1,1,1,-1,0};
template<class T> ostream& operator<<(ostream &os,const vector<T> &v) {
    ITR(i,begin(v),end(v))os<<*i<<(i==end(v)-1?"":" ");return os;}
template<class T> istream& operator>>(istream &is,vector<T> &v) {
    ITR(i,begin(v),end(v)) is>>*i;return is;}
template<class T,class U> istream& operator>>(istream &is, pair<T,U> &p) {
    is>>p.first>>p.second;return is;}
template<class T> bool chmax(T &a,const T &b){if(a<b){a=b;return 1;}return 0;}
template<class T> bool chmin(T &a,const T &b){if(a>b){a=b;return 1;}return 0;}
template<class T> using heap=priority_queue<T,vector<T>,greater<T>>;
struct{template<class T> operator T(){T x;cin>>x;return x;}} IN;
struct before_main_function {
    before_main_function() {
        cin.tie(0);ios::sync_with_stdio(false);
        cout<<setprecision(15)<<fixed;
        #define endl "\n"
    }
} before_main_function;
//------------------8<------------------------------------8<--------------------

signed main() {
    int N=IN;
    vector<string> S(N);
    cin>>S;
    vector<vector<int>> p(N,vector<int>(N,true));
    REP(i,N) REP(j,N) p[i][j]=S[i][j]!='#';

    int ans=0;
    vector<pii> pos={{0,0},{0,1},{1,0},{1,1}};
    vector<int> dir(4,0);
    function<void(int,int)> dfs=[&](int idx,int cnt) {
        if(idx==4) {
            auto q=p;
            REP(t,2) {
                int tmp=cnt;
                p=q;
                auto X=[&]() {
                    REP(i,2) {
                        REPF(j,2,N) {
                            if(p[i][j]) {
                                bool f=true;
                                REP(k,N-1) if(!p[i+k][j]) f=false;
                                if(f) {
                                    REP(k,N-1) p[i+k][j]=false;
                                    tmp++;
                                }
                            }
                        }
                    }
                };
                auto Y=[&]() {
                    REP(j,2) {
                        REPF(i,2,N) {
                            if(p[i][j]) {
                                bool f=true;
                                REP(k,N-1) if(!p[i][j+k]) f=false;
                                if(f) {
                                    REP(k,N-1) p[i][j+k]=false;
                                    tmp++;
                                }
                            }
                        }
                    }
                };
                if(t==0) {X(),Y();}
                else {Y(),X();}
                chmax(ans,tmp);
            }
            return;
        }
        int y=pos[idx].first,x=pos[idx].second;
        auto q=p;
        if(p[y][x]) {
            REP(d,2) {
                bool f=true;
                REP(k,N-1) {
                    if(d==0) {
                        if(!p[y][x+k]) f=false;
                    } else {
                        if(!p[y+k][x]) f=false;
                    }
                }
                if(f) {
                    REP(k,N-1) {
                        if(d==0) p[y][x+k]=false;
                        else p[y+k][x]=false;
                    }
                    dir[idx]=d+1;
                    dfs(idx+1,cnt+1);
                    p=q;
                }
            }
        }
        dir[idx]=0;
        dfs(idx+1,cnt);
    };
    dfs(0,0);
    cout<<ans<<endl;
    return 0;
}