#include<iostream>
#include<string>
#include<algorithm>
#include<utility>
#include<vector>
#define LL long long
using namespace std;


typedef pair<int, int> P;

int res = 6;
int cnt[6];
string judge[6];
int N,M;

vector<P> ch;
void calc(){
	for (int i = 0; i < N; i++){
		cnt[i] = 0;
		for (int j = 0; j < N; j++){
			if (judge[i][j] == 'o')cnt[i]++;
		}
	}
	int k = 1;
	for (int i = N - 1; i >= 0; i--){
		bool f = false;
		for (int j = 0; j < 6; j++){
			if (cnt[j] == i)
				f = true;
		}
		if (cnt[0] == i)
			res = min(res, k);
		if (f)k++;
	}
}

void backtrack(int n){
	if (n == M){
		calc();
	}
	else{
		judge[ch[n].first][ch[n].second] = 'o';
		judge[ch[n].second][ch[n].first] = 'x';
		backtrack(n + 1);
		judge[ch[n].first][ch[n].second] = 'x';
		judge[ch[n].second][ch[n].first] = 'o';
		backtrack(n + 1);
	}

}

int main(){
	cin >> N;
	res = N;
	for (int i = 0; i < N; i++){
		cin >> judge[i];
		
	}

	for (int i = 0; i < N; i++){
		for (int j = i+1; j < N; j++){
			if (judge[i][j] == '-')ch.push_back(make_pair(i, j));
		}
	}
	M = (int)ch.size();
	backtrack(0);
	cout << res << endl;
}