#include <algorithm>
#include <iostream>
#include <cstdio>
#include <map>
#include <numeric>
#include <cmath>
#include <set>
#include <sstream>
#include <string>
#include <vector>
#include <queue>
#include <stack>
#include <complex>
#include <string.h>
#include <unordered_set>
#include <unordered_map>
#include <tuple>
#include <iomanip>
using namespace std;

#define endl '\n'
#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()
#define uniq(v) (v).erase(unique((v).begin(), (v).end()), (v).end())

typedef long long ll;
typedef pair<int, int> P;
typedef unsigned int uint;
typedef unsigned long long ull;
struct pairhash {
public:
    template<typename T, typename U>
    size_t operator()(const pair<T, U> &x) const {
	size_t seed = hash<T>()(x.first);
	return hash<U>()(x.second) + 0x9e3779b9 + (seed<<6) + (seed>>2);
    }
};

const int inf = 1000000009;
const double eps = 1e-8;
string s[6];
int c = 0;

int search(int k, int l, int n) {
    if (k == n) {
	int score[6];
	memset(score, 0, sizeof(score));
	int mys = 0;
	for (int i = 0; i < n; i++) {
	    if (s[0][i] == 'o')
		mys++;
	}
	score[mys]++;
	for (int i = 1; i < n; i++) {
	    int sc = 0;
	    for (int j = 0; j < n; j++)
		if (s[i][j] == 'o')
		    sc++;
	    score[sc]++;
	}
	
	int res = 0;
	for (int i = 5; i >= 0; i--) {
	    if (score[i] > 0) {
		res++;
		if (i == mys) {
		    return res;
		}
	    }
	}
	return inf;
    } else {
	int nk, nl;
	if (l >= n-1) {
	    nk = k+1;
	    nl = k+2;
	} else {
	    nk = k;
	    nl = l+1;
	}

	int res = 10;
	if (k < n && l < n && s[k][l] == '-') {
	    s[k][l] = 'o'; s[l][k] = 'x';
	    res = search(nk, nl, n);
	    s[k][l] = 'x'; s[l][k] = 'o';
	    res = min(res, search(nk, nl, n));
	    s[l][k] = s[k][l] = '-';
	}
	return (res > 9 ? search(nk, nl, n) : res);
    }
}

int solve(int n) {
    for (int i = 0; i < n; i++)
	cin >> s[i];

    return search(0, 1, n);
}

int main() {

    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << fixed << setprecision(15);

    int n;
    cin >> n;
    cout << solve(n) << endl;
}