// No.43 野球の試合
#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

int main() {
    int N;
    cin >> N;
    vector<vector<char>> s(N, vector<char>(N));
    for (int i = 0; i < N; ++i) {
        for (int j = 0; j < N; ++j) cin >> s[i][j];
    }
    vector<pair<int, int>> unknown;
    vector<int> win(N);
    for (int i = 0; i < N; ++i) {
        for (int j = i + 1; j < N; ++j) {
            if (s[i][j] == '-') unknown.emplace_back(i, j);
            if (s[i][j] == 'o') win[i]++;
            if (s[i][j] == 'x') win[j]++;
        }
    }
    auto calc = [](int t, vector<int> &win) {
        sort(win.begin(), win.end());
        win.erase(unique(win.begin(), win.end()), win.end());
        auto itr = lower_bound(win.begin(), win.end(), t);
        return (int)(win.end() - itr);
    };
    int res = 1 << 30;
    if (unknown.size()) {
        for (int bit = 0; bit < (1 << unknown.size()); ++bit) {
            auto tmp = win;
            for (int i = 0; i < unknown.size(); ++i) {
                if (bit >> i & 1) {
                    tmp[unknown[i].first]++;
                } else {
                    tmp[unknown[i].second]++;
                }
            }
            res = min(res, calc(tmp[0], tmp));
        }
    } else {
        res = calc(win[0], win);
    }
    cout << res << endl;
}