#include <iostream>
using namespace std;

int N;
string match[10];

int win[10];
int sum[10];

int dfs(int id){
    if(id >= N * N){
        for(int i=0;i<N;i++)sum[i] = 0;
        for(int i=0;i<N;i++){
            win[i] = 0;
            for(int j=0;j<N;j++)if(match[i][j] == 'o')++win[i];
            sum[win[i]] = 1;
        }
        for(int i=N-2;i>=0;i--){
            sum[i] += sum[i+1];
        }
        return sum[win[0]];
    }
   
    int res = 100;
    int y = id / N, x = id % N;
    
    if(match[y][x] == '-'){
        match[y][x] = 'o';
        match[x][y] = 'x';
        
        res = min(res, dfs(id + 1));
        
        match[y][x] = 'x';
        match[x][y] = 'o';
        
        res = min(res, dfs(id + 1));
        
        match[y][x] = '-';
        match[x][y] = '-';
    } else {
        res = dfs(id + 1);
    }
    
    return res;
}
int main(){
    cin >> N;
    for(int i=0;i<N;i++)cin >> match[i];
    
    cout << dfs(0) << endl;
    return 0;
}