import sys
input = sys.stdin.readline

N=int(input())
MAP=[input().strip() for i in range(N)]

flag=1

for i in range(N):
    if MAP[0][i]=="#":
        flag=0

    if MAP[0][N-1]=="#":
        flag=0

    if MAP[i][0]=="#":
        flag=0

    if MAP[N-1][0]=="#":
        flag=0

if flag==1:
    ANS=4
else:
    ANS=0

score=0
for i in range(N):
    if not ("#" in MAP[i][0:N-1]):
        score+=1

flag=1

for i in range(N-1):
    if MAP[i][N-1]=="#":
        flag=0

if flag==0:
    flag=1
    for i in range(1,N):
        if MAP[i][N-1]=="#":
            flag=0


ANS=max(ANS,score+flag)

score=0
for i in range(N):
    if not ("#" in MAP[i][1:N]):
        score+=1

flag=1

for i in range(N-1):
    if MAP[i][0]=="#":
        flag=0

if flag==0:
    flag=1
    for i in range(1,N):
        if MAP[i][0]=="#":
            flag=0

ANS=max(ANS,score+flag)

score=0

for i in range(N):
    if not ("#" in MAP[i][1:N]) or not ("#" in MAP[i][0:N-1]):
        score+=1

ANS=max(ANS,score)

MAP2=[["."]*N for i in range(N)]
for i in range(N):
    for j in range(N):
        if MAP[i][j]=="#":
            MAP2[N-1-j][i]="#"

MAP=MAP2

score=0
for i in range(N):
    if not ("#" in MAP[i][0:N-1]):
        score+=1

flag=1

for i in range(N-1):
    if MAP[i][N-1]=="#":
        flag=0

if flag==0:
    flag=1
    for i in range(1,N):
        if MAP[i][N-1]=="#":
            flag=0

ANS=max(ANS,score+flag)

score=0
for i in range(N):
    if not ("#" in MAP[i][1:N]):
        score+=1

flag=1

for i in range(N-1):
    if MAP[i][0]=="#":
        flag=0

if flag==0:
    flag=1
    for i in range(1,N):
        if MAP[i][0]=="#":
            flag=0

ANS=max(ANS,score+flag)

score=0

for i in range(N):
    if not ("#" in MAP[i][1:N]) or not ("#" in MAP[i][0:N-1]):
        score+=1

ANS=max(ANS,score)

print(ANS)