import sys

sys.setrecursionlimit(200005)
int1 = lambda x: int(x)-1
p2D = lambda x: print(*x, sep="\n")
def II(): return int(sys.stdin.readline())
def LI(): return list(map(int, sys.stdin.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def LI1(): return list(map(int1, sys.stdin.readline().split()))
def LLI1(rows_number): return [LI1() for _ in range(rows_number)]
def SI(): return sys.stdin.readline().rstrip()
dij = [(0, 1), (-1, 0), (0, -1), (1, 0)]
# dij = [(0, 1), (-1, 0), (0, -1), (1, 0), (1, 1), (1, -1), (-1, 1), (-1, -1)]
# inf = 18446744073709551615
inf = 4294967295
md = 10**9+7
# md = 998244353

def rot90(aa):
    return [col[::-1] for col in zip(*aa)]

def cnt1(aa):
    res = 0
    for row in aa:
        if sum(row[:-1]) == n-1 or sum(row[1:]) == n-1: res += 1
    return res

def cnt2(aa):
    for i in range(n-1):
        if aa[i][0] == 0: return 0
    res = 1
    for row in aa[:-1]:
        if sum(row[1:]) == n-1: res += 1
    if sum(aa[-1][:-1]) == n-1 or sum(aa[-1][1:]) == n-1: res += 1
    return res

def cnt3(aa):
    if sum(aa[0]) < n: return 0
    if sum(aa[-1]) < n: return 0
    if sum(aa[i][0] for i in range(n)) < n: return 0
    if sum(aa[i][-1] for i in range(n)) < n: return 0
    return 4

n = II()
aa = [[c == "." for c in SI()] for _ in range(n)]

ans = 0
ans = max(ans, cnt1(aa))
aa = rot90(aa)
ans = max(ans, cnt1(aa))

for _ in range(2):
    for _ in range(4):
        ans = max(ans, cnt2(aa))
        aa = rot90(aa)
    aa = aa[::-1]

ans = max(ans, cnt3(aa))

print(ans)