# coding: utf-8
# Your code here!

import copy

n = int(input())
score_list = []
for i in range(n):
    score_list.append(list(input()))
    
super_list = []
sum_all = sum([e for e in range(1, n)])
count = 0
border_list = list(range(n - 1, 0, -1))
cumu_list = []
rank_list = []

for i in range(n):
    cur_list = score_list[i][i + 1 :]
    super_list.extend(cur_list)

for j in range(len(border_list)):
    if j == 0:
        cumu_list.append(border_list[0])
    else:
        cumu_list.append(cumu_list[j - 1] + border_list[j])

for i in range(2 ** sum_all):
    cur_list = []
    flag = 1
    
    for j in range(sum_all):
        if (i >> j) & 1 == 1:
            cur_list.append('o')
        else:
            cur_list.append('x')
    
    for j in range(sum_all):
        if super_list[j] == 'x' and cur_list[j] == 'o':
            flag = 0
            break
        if super_list[j] == 'o' and cur_list[j] == 'x':
            flag = 0
            break
        
    # prediction equals given
    if flag == 1:
        res_list = [[] for j in range(n - 1)]
        map_list = copy.copy(score_list)
            
        for j in range(len(cur_list)):
            for k in range(len(border_list)):
                if j < cumu_list[k]:
                    res_list[k].append(cur_list[j])
                    break

        for l in range(n - 1):
            begin = l + 1
            for j in range(n - (l + 1)):
                right = res_list[l][j]
                wrong = None
                if right == 'o':
                    wrong = 'x'
                elif right == 'x':
                    wrong = 'o'
                elif right == '-':
                    right = 'o'
                    wrong = 'x'
                    
                map_list[l][begin] = right
                map_list[begin][l] = wrong
                begin += 1
                
        # for i in range(n):
        #     print(map_list[i])
        # print('---------------')
        
        win_count_list = []
        for i in range(n):
            win_count_list.append(map_list[i].count('o'))
        
        k_rank = sorted(set(win_count_list), \
                        key=win_count_list.index, reverse=True).index(win_count_list[0]) + 1
        rank_list.append(k_rank)
        
        
res = min(rank_list)

print(res)