#include <atcoder/all>
#include <bits/stdc++.h>
using namespace std;
using namespace atcoder;
#define rep(i, n) REP(i, 0, n)
#define REP(i, s, e) for (ll i = (s); i < (ll)(e); i++)
#define repr(i, n) REPR(i, n, 0)
#define REPR(i, s, e) for (ll i = (ll)(s - 1); i >= (ll)(e); i--)
#define all(r) r.begin(), r.end()
#define rall(r) r.rbegin(), r.rend()

typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vl;

template <typename T, typename U>
bool chmax(T& a, const U& b) {
    if (a >= b) return false;
    a = b;
    return true;
}
template <typename T, typename U>
bool chmin(T& a, const U& b) {
    if (a <= b) return false;
    a = b;
    return true;
}

void yes_no(bool f, string yes = "Yes", string no = "No") {
    cout << (f ? yes : no) << "\n";
}

void solve() {
    int n;
    cin >> n;
    vector<string> s(n);
    rep(i, n) cin >> s[i];
    rep(i, n) if (s[0][i] == '-') {
        s[0][i] = 'o';
        s[i][0] = 'x';
    }
    using P = pair<int, int>;
    vector<P> vs;
    rep(i, n) rep(j, i) if (s[i][j] == '-') {
        vs.emplace_back(i, j);
    }
    int ans = 1e9;
    int m = vs.size();
    rep(mask, 1 << m) {
        rep(i, m) {
            s[vs[i].first][vs[i].second] = (mask & (1 << i)) ? 'o' : 'x';
            s[vs[i].second][vs[i].first] = (mask & (1 << i)) ? 'x' : 'o';
        }
        vector<vi> win(n);
        rep(i, n) {
            int cnt = 0;
            rep(j, n) if (s[i][j] == 'o') cnt++;
            win[cnt].emplace_back(i);
        }
        int cnt = 0;
        repr(i, n) {
            if (win[i].empty()) continue;
            cnt++;
            rep(j, win[i].size()) if (win[i][j] == 0) chmin(ans, cnt);
        }
    }
    cout << ans << "\n";
}

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    int t = 1;
    // cin >> t;
    rep(ti, t) solve();
    return 0;
}