#include <bits/stdc++.h>
#define EPS 1e-9
#define INF 1070000000LL
#define MOD 1000000007LL
#define fir first
#define foreach(it,X) for(auto it=(X).begin();it!=(X).end();it++)
#define numa(x,a) for(auto x: a)
#define ite iterator
#define mp make_pair
#define mt make_tuple
#define rep(i,n) rep2(i,0,n)
#define rep2(i,m,n) for(int i=m;i<(n);i++)
#define pb push_back
#define pf push_front
#define sec second
#define sz(x) ((int)(x).size())
#define ALL( c ) (c).begin(), (c).end()
#define gcd(a,b) __gcd(a,b)
#define mem(x,n) memset(x,n,sizeof(x))
#define endl "\n"
using namespace std;
template <int POS, class TUPLE> void deploy(std::ostream &os, const TUPLE &tuple){}
template <int POS, class TUPLE, class H, class ...Ts> void deploy(std::ostream &os, const TUPLE &t){ os << (POS == 0 ? "" : ", ") << get<POS>(t); deploy<POS + 1, TUPLE, Ts...>(os, t); }
template <class T> std::ostream& operator<<(std::ostream &os, std::vector<T> &v){ int remain = v.size(); os << "{"; for(auto e: v) os << e << (--remain == 0 ? "}" : ", "); return os; }
template <class T> std::ostream& operator<<(std::ostream &os, std::set<T> &v){ int remain = v.size(); os << "{"; for(auto e: v) os << e << (--remain == 0 ? "}" : ", "); return os; }
template <class T, class K> std::ostream& operator<<(std::ostream &os, std::map<T, K> &mp){ int remain = mp.size(); os << "{"; for(auto e: mp) os << "(" << e.first << " -> " << e.second << ")" << (--remain == 0 ? "}" : ", "); return os; }
#define DEBUG1(var0) { std::cerr << (#var0) << "=" << (var0) << endl; }
#define DEBUG2(var0, var1) { std::cerr << (#var0) << "=" << (var0) << ", ";DEBUG1(var1); }
#define DEBUG3(var0, var1, var2) { std::cerr << (#var0) << "=" << (var0) << ", ";DEBUG2(var1,var2); }
#define DEBUG4(var0, var1, var2, var3) { std::cerr << (#var0) << "=" << (var0) << ", ";DEBUG3(var1,var2,var3); }
using ll = long long;

int nums[10][10];
vector <pair <int,int> > memo;
int memo2[70];
int N;
int judge(){
  rep(i,sz(memo)){
    auto x = memo[i];
    nums[x.fir][x.sec] = memo2[i];
    nums[x.sec][x.fir] = - memo2[i];
  }
  vector <pair <int,int> > team;
  rep(i,N){
    int w = 0;
    rep(j,N){
      if(nums[i][j] == 1){
        w++;
      }
    }
    team.pb(mp(w,i));
  }
  sort(ALL(team),greater<pair <int,int> >());
  int ww = 0;
  int pl = 0;
  rep(i,N){
    if(ww != team[i].fir){
      ww = team[i].fir;
      pl += 1;
    }
    if(team[i].sec == 0){
      return pl;
    }
  }
  //return 1;
}

int go(int now){
  if(now == sz(memo)){
    return judge();
  }
  memo2[now] = 1;//w
  int ret = go(now+1);
  memo2[now] = -1;//l
  ret = min(ret,go(now+1));
  return ret;
}

int main(){
  cin.tie(0);
  ios_base::sync_with_stdio(0);
  cin >> N;
  rep(i,N){
    rep(j,N){
      char c;
      cin >> c;
      if(i == j){
        continue;
      }
      if(c == 'o'){
        nums[i][j] = 1;
      }else if(c == 'x'){
        nums[i][j] = -1;
      }else{
        if(i == 0){
          nums[i][j] = 1;
          nums[j][i] = 1;
        }else if(i < j){
          memo.pb(mp(i,j));
        }
      }
    }
  }
  cout << go(0) << endl;
  return 0;
}