#include<iostream>
#include<set>
using namespace std;

int n;
char table[6][6] = {};
int ans = 7;

void solve(char T[6][6]){
    bool found = false;

    for(int i = 0; i < n; i++){
        for(int j = 0; j < n; j++){
            if(T[i][j] == '-'){
                found = true;
                T[i][j] = 'o'; T[j][i] = 'x';
                solve(T);

                T[i][j] = 'x'; T[j][i] = 'o';
                solve(T);

                T[i][j] = T[j][i] = '-';
            }
        }
    }

    if(!found){
        int zero = 0;
        for(int j = 0; j < n; j++)  if(T[0][j] == 'o')  zero++;
        set<int> score;
        score.insert(zero);
        for(int i = 1; i < n; i++){
            int tmp = 0;
            for(int j = 0; j < n; j++)  if(T[i][j] == 'o')  tmp++;
            score.insert(tmp);
        }

        int pos = 1;
        for(set<int>::reverse_iterator it = score.rbegin(); it != score.rend(); it++){
            if(*it == zero){
                ans = min(ans, pos);
                break;
            }
            pos++;
        }
    }
}

int main(){
    cin >> n;

    for(int i = 0; i < n; i++){
        for(int j = 0; j < n; j++){
            cin >> table[i][j];
        }
    }

    solve(table);

    cout << ans << endl;

    return 0;
}