N = gets.to_i
S = N.times.map{
  gets[0,N]
}
res = N.times.map{[nil]*N}
S.each_with_index{|s, i|
  s.chars.each_with_index{|c, ii|
    res[i][ii] = c
  }
}
N.times{|x|
  if res[0][x] == ?-
    res[0][x] = ?o
    res[x][0] = ?x
  end
}


def f(res)
  if !res.any?{|a|a.any?{|c|c == ?-}}
    win = res[0].count(?o)
    return 1 + res.map{|a|a.count(?o)}.sort_by{|o|-o}.uniq.index(win)
  end
  N.times.map{|y|
    N.times.map{|x|
      next 9e9 if res[y][x] != ?-
      res[y][x] = ?o
      res[x][y] = ?x
      f(res).tap{
        res[y][x] = ?-
        res[x][y] = ?-
      }
    }.min
  }.min
end
p f(res)