N = int(input())
S = []
S_ = [[] for _ in range(N)]
for _ in range(N):
    tmp = []
    for i, c in enumerate(input()):
        tmp.append(c)
        S_[i].append(c)
    S.append(tmp)

num1 = 0
edge = S_[N - 1]
for i, row in enumerate(S):
    if '#' not in row[:N - 1]:
        num1 += 1
    elif '#' not in row[1:]:
        num1 += 1
        edge[i] = '#'
if '#' not in edge[:N - 1] or '#' not in edge[1:]:
    num1 += 1
# print(num1)

num2 = 0
edge = S_[0]
for i, row in enumerate(S):
    if '#' not in row[1:]:
        num2 += 1
    elif '#' not in row[:N - 1]:
        num2 += 1
        edge[i] = '#'
if '#' not in edge[:N - 1] or '#' not in edge[1:]:
    num2 += 1
# print(num2)

num3 = 0
edge = S[N - 1]
for i, row in enumerate(S_):
    if '#' not in row[:N - 1]:
        num3 += 1
    elif '#' not in row[1:]:
        num3 += 1
        edge[i] = '#'
if '#' not in edge[:N - 1] or '#' not in edge[1:]:
    num3 += 1
# print(num3)

num4 = 0
edge = S[0]
for i, row in enumerate(S_):
    if '#' not in row[1:]:
        num4 += 1
    elif '#' not in row[:N - 1]:
        num4 += 1
        edge[i] = '#'
if '#' not in edge[:N - 1] or '#' not in edge[1:]:
    num4 += 1
# print(num4)

print(max(num1, num2, num3, num4))