#include <cstring>
#include <iostream>
#include <vector>
#include <string>
#include <map>
#include <queue>
#include <algorithm>

int dfs(char strs[8][8], int wins[8], int n) {
  for(int i = 0; i < n; ++i) {
    for(int j = i + 1; j < n; ++j) {
      if( strs[i][j] == '-' ) {
        strs[i][j] = 'o';
        wins[i] += 1;
        int res = dfs(strs, wins, n);
        wins[i] -= 1;
        strs[i][j] = '-';

        strs[i][j] = 'x';
        wins[j] += 1;
        res = std::min(res, dfs(strs, wins, n));
        wins[j] -= 1;
        strs[i][j] = '-';
        return res;
      }
    }
  }
  int res = 1;
  int t[8] = {};
  for(int i = 0; i < n; ++i) {
    t[wins[i]] += 1;
  }
  for(int i = wins[0] + 1; i < 8; ++i) {
    if( t[i] != 0 ) res += 1;
  }
  return res;
}

int main() {

  char strs[8][8];
  int  wins[8] = {};
  int  n;

  scanf("%d", &n);
  for(int i = 0; i < n; ++i) {
    scanf("%s", strs[i]);
  }

  for(int i = 0; i < n; ++i) {
    for(int j = 0; j < n; ++j) {
      if( strs[i][j] == 'o' ) {
        wins[i] += 1;
      }
    }
  }

  printf("%d\n", dfs(strs, wins, n));
  
  return 0;
}