import sys
input = sys.stdin.readline

N=int(input())
MAP=[list(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

for ix in range(N):
    if not ("#" in MAP[ix][0:N-1]):
        for j in range(N-1):
            MAP[ix][j]="#"

        score=1

        for j in range(N):
            x=0
            for i in range(N):
                if MAP[i][j]==".":
                    x+=1
                else:
                    x=0

                if x>=N-1:
                    score+=1
                    break

        ANS=max(ANS,score)

        for j in range(N-1):
            MAP[ix][j]="."

    if not ("#" in MAP[ix][1:N]):
        for j in range(1,N):
            MAP[ix][j]="#"

        score=1

        for j in range(N):
            x=0
            for i in range(N):
                if MAP[i][j]==".":
                    x+=1
                else:
                    x=0

                if x>=N-1:
                    score+=1
                    break

        ANS=max(ANS,score)

        for j in range(1,N):
            MAP[ix][j]="."

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

for ix in range(N):
    if not ("#" in MAP[ix][0:N-1]):
        for j in range(N-1):
            MAP[ix][j]="#"

        score=1

        for j in range(N):
            x=0
            for i in range(N):
                if MAP[i][j]==".":
                    x+=1
                else:
                    x=0

                if x>=N-1:
                    score+=1
                    break

        ANS=max(ANS,score)

        for j in range(N-1):
            MAP[ix][j]="."

    if not ("#" in MAP[ix][1:N]):
        for j in range(1,N):
            MAP[ix][j]="#"

        score=1

        for j in range(N):
            x=0
            for i in range(N):
                if MAP[i][j]==".":
                    x+=1
                else:
                    x=0

                if x>=N-1:
                    score+=1
                    break

        ANS=max(ANS,score)

        for j in range(1,N):
            MAP[ix][j]="."

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)