import sys
import copy
def check_board(board, N):
ret = 0
for i in range(N):
res = 1
for j in range(N - 1):
if board[i][j] == board[i][j + 1]:
res += 1
if res > ret:
ret = res
for i in range(N):
res = 1
for j in range(N - 1):
if board[j][i] == board[j + 1][i]:
res += 1
if res > ret:
ret = res
return ret
N = int(sys.stdin.readline())
board = []
candy_cnt = 0
for i in range(N):
board.append(sys.stdin.readline().replace('\n', ''))
for i in range(N):
for j in range(N - 1):
tmp = copy.deepcopy(board)
if tmp[i][j] != tmp[i][j + 1]:
tmp[i] = tmp[i][:j] + tmp[i][j + 1] + tmp[i][j] + tmp[i][j + 2:]
res = check_board(tmp, N)
if res > candy_cnt:
candy_cnt = res
for i in range(N):
for j in range(N - 1):
tmp = copy.deepcopy(board)
if tmp[j][i] != tmp[j + 1][i]:
tmp_row = tmp[j][:i] + tmp[j + 1][i] + tmp[j][i + 1:]
tmp[j + 1] = tmp[j + 1][:i] + tmp[j][i] + tmp[j + 1][i + 1:]
tmp[j] = tmp_row
res = check_board(tmp, N)
if res > candy_cnt:
candy_cnt = res
print(candy_cnt)
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