#include<bits/stdc++.h>
#define rep(i,a,b) for(int i=int(a);i<int(b);++i)
using namespace std;
typedef long long ll;
typedef pair<int,int> P;
int INF = (1LL << 30) - 1;
int MOD = 1e9+7;
main(){
    int N;
    cin >> N;
    vector<string> S(N);
    rep(i,0,N)cin >> S[i];

    int cnt = 0;
    vector< P > V;
    rep(i,0,N)rep(j,i,N){
        if(S[i][j] == '-'){
            cnt++;
            V.push_back(P(i,j));
        }
    }
    int mini = INF;
    rep(i,0,1 << cnt){
        rep(j,0,cnt){
            bool flag = i & (1 << j);
            
            int x = V[j].second,y = V[j].first;
            S[y][x] = "ox"[flag];
            S[x][y] = "xo"[flag];
        
        }
    /*
    cout  << endl;
    rep(j,0,N)cout << S[j] << endl;
    cout  << endl;
    */
        vector< P > win(N);
        rep(j,0,N)win[j].second = j;

        //for(auto p:win)cout << p.first << " " << p.second << endl;

        rep(j,0,N)rep(k,0,N){
            if(S[j][k] == 'o')win[j].first ++;
        }
        sort(win.rbegin(), win.rend());
        int rank = 1,num = win[0].first;
        rep(j,0,N){
            if(num != win[j].first){
                num = win[j].first;
                rank++;
            }
            if(win[j].second == 0)mini = min(mini, rank);
        }
    }
    cout << mini << endl;
}