def sol n,d,w,c,memo
    if memo[c] <= n
        return memo[c]
    end
    if c == 0
        return w.uniq.sort.reverse.index(w[0]) + 1
    end
    ans = n
    n.times{|i|
        (i + 1).upto(n - 1){|j|
            if d[i][j] == '-'
                d[i][j] = 'o'
                d[j][i] = 'x'
                w[i] += 1
                ans = [ans, sol(n,d,w,c - 2,memo)].min
                d[i][j] = 'x'
                d[j][i] = 'o'
                w[i] -= 1
                w[j] += 1
                ans = [ans, sol(n,d,w,c - 2,memo)].min
                d[i][j] = '-'
                d[j][i] = '-'
                w[j] -= 1
            end
            }
        }
    memo[c] = [ans, memo[c]].min
    return ans
end

n = gets.to_i
d = Array.new(n)
w = Array.new(n,0)
c = 0

n.times{|i|
    d[i] = gets.chomp.split('')
    n.times{|j|
        if d[i][j] == 'o'
            w[i] += 1
        elsif d[i][j] == '-'
            c += 1
        end
        }
    }

memo = Array.new(c + 1, n + 1)
p sol(n,d,w,c,memo)