#include #define rep(i, n) for (int i = 0; i < int(n); i++) #define rrep(i, n) for (int i = int(n) - 1; i >= 0; i--) #define reps(i, n) for (int i = 1; i <= int(n); i++) #define rreps(i, n) for (int i = int(n); i >= 1; i--) #define repc(i, n) for (int i = 0; i <= int(n); i++) #define rrepc(i, n) for (int i = int(n); i >= 0; i--) #define repi(i, a, b) for (int i = int(a); i < int(b); i++) #define repic(i, a, b) for (int i = int(a); i <= int(b); i++) #define repp(i, n) rep(i, n) #define reppp(i, n) repp(i, n) #define rrepp(i, n) rrep(i, n) #define repss(i, n) reps(i, n) #define repcc(i, n) repc(i, n) #define repii(i, a, b) repi(i, a, b) #define each(x, y) for (auto &x : y) #define all(a) (a).begin(), (a).end() #define bit(b) (1ll << (b)) using namespace std; using i32 = int; using i64 = long long; using u64 = unsigned long long; using f80 = long double; using vi32 = vector; using vi64 = vector; using vu64 = vector; using vf80 = vector; using vstr = vector; inline void yes() { cout << "Yes" << '\n'; exit(0); } inline void no() { cout << "No" << '\n'; exit(0); } inline i64 gcd(i64 a, i64 b) { if (min(a, b) == 0) return max(a, b); if (a % b == 0) return b; return gcd(b, a % b); } inline i64 lcm(i64 a, i64 b) { return a / gcd(a, b) * b; } inline u64 xorshift() { static u64 x = 88172645463325252ull; x = x ^ (x << 7); return x = x ^ (x >> 9); } void solve(); int main() { ios::sync_with_stdio(0); cin.tie(0); cout << fixed << setprecision(16); solve(); return 0; } template class pqasc : public priority_queue, greater> {}; template class pqdesc : public priority_queue, less> {}; template inline void amax(T &x, T y) { if (x < y) x = y; } template inline void amin(T &x, T y) { if (x > y) x = y; } template inline T power(T x, i64 n, T e = 1) { T r = e; while (n > 0) { if (n & 1) r *= x; x *= x; n >>= 1; } return r; } template istream& operator>>(istream &is, vector &v) { each(x, v) is >> x; return is; } template ostream& operator<<(ostream &os, vector &v) { rep(i, v.size()) { if (i) os << ' '; os << v[i]; } return os; } template istream& operator>>(istream &is, pair &p) { is >> p.first >> p.second; return is; } template ostream& operator<<(ostream &os, pair &p) { os << p.first << ' ' << p.second; return os; } void solve() { int N; cin >> N; vstr s(N); rep(i, N) cin >> s[i]; auto b = vector>(N, vector(N)); function rec = [&](int n) { if (n == N) { int ans; unordered_set se; rep(i, N) { int cnt = 0; rep(j, N) if (i != j && b[i][j]) cnt++; if (i == 0) ans = cnt; if (i > 0 && ans < cnt) se.insert(cnt); } return 1 + (int) se.size(); } int mn = 1e9; rep(i, bit(N - 1)) { bool f = true; rep(j, n) { b[n][j] = (i & bit(j)) != 0; b[j][n] = !b[n][j]; if (s[n][j] == 'o' && !b[n][j]) { f = false; break; } if (s[n][j] == 'x' && b[n][j]) { f = false; break; } } if (f) amin(mn, rec(n + 1)); } return mn; }; cout << rec(0) << '\n'; }