#include <bits/stdc++.h>
#define rep(i, n) for(long long i = 0; i < n; i++)
#define ALL(v) (v).begin(), (v).end()
using namespace std;

using lint = long long;

int main() {
    int n;
    cin >> n;
    vector<vector<char>> s(n, vector<char>(n));
    rep(i, n) {
        rep(j, n) {
            cin >> s[i][j];
        }
    }
    vector<pair<int, int>> v;
    for (int i = 0; i < n; i++) {
        for (int j = i + 1; j < n; j++) {
            if (s[i][j] == '-') {
                v.emplace_back(i, j);
            }
        }
    }
    int sz = v.size();
    auto calc = [&](vector<vector<char>> s) -> int {
        vector<int> cnt(n, 0);
        rep(i, n) rep(j, n) {
            if (s[i][j] == 'o') {
                cnt[i]++;
            }
        }
        vector<vector<int>> lst(100);
        rep(i, n) {
            lst[cnt[i]].emplace_back(i);
        }
        int res = 1;
        for (int i = 99; i >= 0; i--) {
            for (int x : lst[i]) {
                if (x == 0) {
                    return res;
                }
            }
            if (lst[i].size() > 0) {
                res++;
            }
        }
    };
    int ans = 100;
    rep(bit, (1  << sz)) {
        vector<vector<char>> t = s;
        rep(i, sz) {
            auto [x, y] = v[i];
            if (bit & (1 << i)) {
                t[x][y] = 'o';
                t[y][x] = 'x';
            } else {
                t[x][y] = 'x';
                t[y][x] = 'o';
            }
        }
        ans = min(ans, calc(t));
    }
    cout << ans << endl;
}