#include "bits/stdc++.h"

using namespace std;

using ll = long long;
using ld = long double;

const int INF = (1 << 30) - 1;
const ll INF64 = ((ll)1 << 62) - 1;
const double PI = 3.1415926535897932384626433832795;

const int dx[] = { 0, 1, 0, -1 };
const int dy[] = { -1, 0, 1, 0 };

int gcd(int x, int y) { return y ? gcd(y, x % y) : x; }
ll gcd(ll x, ll y) { return y ? gcd(y, x % y) : x; }
int lcm(int x, int y) { return x / gcd(x, y) * y; }
ll lcm(ll x, ll y) { return x / gcd(x, y) * y; }

int main() {
	ios::sync_with_stdio(false);
	cin.tie(0);

	int n;
	cin >> n;

	vector<string> s(n);
	for (auto& v : s) {
		cin >> v;
	}

	vector<pair<int, int>> plans;
	vector<int> win(n);
	for (int i = 0; i < n; i++) {
		for (int j = 0; j < n; j++) {
			if (s[i][j] == 'b') {
				continue;
			}
			
			if (s[i][j] == '-') {
				plans.emplace_back(min(i, j), max(i, j));
				s[i][j] = s[j][i] = 'b';
			} else if (s[i][j] == 'o') {
				win[i]++;
			}
		}
	}

	int ans = INF;
	for (int mask = 0; mask < (1 << plans.size()); mask++) {
		vector<int> scores = win;
		for (int i = 0; i < (int)plans.size(); i++) {
			if (mask & (1 << i)) {
				scores[plans[i].first]++;
			} else {
				scores[plans[i].second]++;
			}
		}

		int yakult = scores[0];
		sort(begin(scores), end(scores), greater<int>());
		scores.erase(unique(begin(scores), end(scores)), end(scores));

		int res = 1;
		while (scores[res - 1] != yakult) {
			res++;
		}

		ans = min(ans, res);
	}

	cout << ans << endl;
	return 0;
}