#include "bits/stdc++.h"
#define REP(i,n,N) for(ll i=(n); i<(N); i++)
#define RREP(i,n,N) for(ll i=(N-1); i>=n; i--)
#define CK(n,a,b) ((a)<=(n)&&(n)<(b))
#define ALL(v) (v).begin(),(v).end()
#define p(s) cout<<(s)<<endl
#define p2(a,b) cout<<(a)<<" "<<(b)<<endl
#define v2(T) vector<vector<T>>
typedef long long ll;
using namespace std;
const ll inf=1e18;

ll N;
string s[6];

int main(){
    while(cin>>N){
        REP(i,0,N){
            cin>>s[i];
        }
        ll ans=10;
        vector<ll> win(6);
        vector<pair<ll,ll>> ca; //{i,j}:0 i win , 1 j win
        REP(i,0,N){
            REP(j,i+1,N){
                if(s[i][j]=='o')  win[i]++;
                else if(s[i][j]=='x') win[j]++;
                else ca.push_back({i,j});
            }
        }
        REP(mask,0,(1<<ca.size())){
            vector<ll> score = win;
            REP(i,0,ca.size()) {
                if(mask & (1<<i)) {
                    score[ca[i].second]++;
                }else{
                    score[ca[i].first]++;
                }
            }
            set<ll> s;
            s.insert(score[0]);
            REP(i,1,N){
                if(score[i]>score[0]){
                    s.insert(score[i]);
                }

            }
            ans=min<ll>(ans,s.size());
        }
        p(ans);
    }

    return 0;
}