#include "bits/stdc++.h"
using namespace std;

typedef long long Int;
#define REP(i,n) for(int (i)=0;(i)<(int)(n);++(i))


int best_rank;
void f(int a, int b, vector<string>& t, const int n) {
	if (a == n) {
		vector<int> win(n);
		REP(i, n) REP(j, n) if (t[i][j] == 'o') win[i]++;
		set<int> s;
		for (int i = 1; i < n; i++) if (win[0] > win[i]) s.insert(win[i]);
		int rank = s.size() + 1;
		if (best_rank > rank) { best_rank = rank; }
		return;
	}
	int na = a;
	int nb = b;
	nb++;
	if (nb >= n) { na++; nb = 0; }

	if (t[a][b] == '-') {
		t[a][b] = 'o';
		t[b][a] = 'x';
		f(na, nb, t, n);
		t[a][b] = 'x';
		t[b][a] = 'o';
		f(na, nb, t, n);
		t[a][b] = '-';
		t[b][a] = '-';
	}
	else {
		f(na, nb, t, n);
	}
}

int main() {
	int n; cin >> n;
	vector<string> t(n);
	REP(i, n) cin >> t[i];
	best_rank = n;
	f(0, 0, t, n);
	cout << best_rank << endl;
}