#include <bits/stdc++.h>
#define For(i, a, b) for(int (i)=(int)(a); (i)<(int)(b); ++(i))
#define rFor(i, a, b) for(int (i)=(int)(a)-1; (i)>=(int)(b); --(i))
#define rep(i, n) For((i), 0, (n))
#define rrep(i, n) rFor((i), (n), 0)
#define fi first
#define se second
using namespace std;
typedef long long lint;
typedef unsigned long long ulint;
typedef pair<int, int> pii;
typedef pair<lint, lint> pll;
template<class T> bool chmax(T &a, const T &b){if(a<b){a=b; return true;} return false;}
template<class T> bool chmin(T &a, const T &b){if(a>b){a=b; return true;} return false;}
template<class T> T div_floor(T a, T b){
    if(b < 0) a *= -1, b *= -1;
    return a>=0 ? a/b : (a+1)/b-1;
}
template<class T> T div_ceil(T a, T b){
    if(b < 0) a *= -1, b *= -1;
    return a>0 ? (a-1)/b+1 : a/b;
}

constexpr lint mod = 1e9+7;
constexpr lint INF = mod * mod;
constexpr int MAX = 200010;

int n, ans;
char c[10][10];

void dfs(int cur, int j){
    if(cur == n-1){
        vector<int> cnt(n, 0);
        rep(i, n)For(k, i+1, n){
            if(c[i][k] == 'o') ++cnt[i];
            else ++cnt[k];
        }
        int a = cnt[0];
        sort(cnt.begin(), cnt.end(), greater<>());
        cnt.erase(unique(cnt.begin(), cnt.end()), cnt.end());
        rep(i, cnt.size())if(cnt[i] == a) chmin(ans, i+1);
        return;
    }
    int ncur, nj;
    if(j == n-1) ncur = cur+1, nj = ncur+1;
    else ncur = cur, nj = j+1;

    if(c[cur][j] != '-') dfs(ncur, nj);
    else{
        c[cur][j] = 'o';
        dfs(ncur, nj);
        c[cur][j] = 'x';
        dfs(ncur, nj);
        c[cur][j] = '-';
    }
}

int main(){
    scanf("%d", &n);
    rep(i, n)rep(j, n) scanf(" %c", &c[i][j]);
    ans = n;
    dfs(0, 1);
    printf("%d\n", ans);
}