Buggy python submission (verdict: Time Limit Exceeded):
def main():
    H, W = map(int, input().split())
    S = [list(input()) for _ in range(H)]
    
    left = [[-1]*W for _ in range(H)]
    right = [[-1]*W for _ in range(H)]
    up = [[-1]*W for _ in range(H)]
    down = [[-1]*W for _ in range(H)]

    for i in range(H):
        for j in range(W):
            if S[i][j] == '.':
                if j == 0:
                    left[i][j] = 0
                else:
                    left[i][j] = left[i][j-1] + 1
                if i == 0:
                    up[i][j] = 0
                else:
                    up[i][j] = up[i-1][j] + 1

            if S[-1-i][-1-j] == '.':
                if j == 0:
                    right[-1-i][-1-j] = 0
                else:
                    right[-1-i][-1-j] = right[-1-i][-1-(j-1)] + 1
                if i == 0:
                    down[-1-i][-1-j] = 0
                else:
                    down[-1-i][-1-j] = down[-1-(i-1)][-1-j] + 1

    ans = 0
    temp = [0] * W
    for i in range(H):
        for j in range(W):
            temp[j] = left[i][j] + right[i][j] + down[i][j] + up[i][j] + 1
        ans = max(ans, max(temp))
    print(ans)

main()

Fixed submission:
def main():
    H, W = map(int, input().split())
    S = [list(input()) for _ in range(H)]

    left = [[-1]*W for _ in range(H)]
    right = [[-1]*W for _ in range(H)]
    up = [[-1]*W for _ in range(H)]
    down = [[-1]*W for _ in range(H)]

    for i in range(H):
        for j in range(W):
            if S[i][j] == '.':
                if j == 0:
                    left[i][j] = 0
                else:
                    left[i][j] = left[i][j-1] + 1

    for i in range(H):
        for j in range(W):
            if S[-1-i][-1-j] == '.':        
                if j == 0:
                    right[-1-i][-1-j] = 0
                else:
                    right[-1-i][-1-j] = right[-1-i][-1-(j-1)] + 1

    for i in range(H):
        for j in range(W):
            if S[i][j] == '.':
                if i == 0:
                    up[i][j] = 0
                else:
                    up[i][j] = up[i-1][j] + 1

    for i in range(H):
        for j in range(W):
            if S[-1-i][-1-j] == '.':
                if i == 0:
                    down[-1-i][-1-j] = 0
                else:
                    down[-1-i][-1-j] = down[-1-(i-1)][-1-j] + 1
            
    ans = 0
    temp = [0] * W
    for i in range(H):
        for j in range(W):
            temp[j] = left[i][j] + right[i][j] + down[i][j] + up[i][j] + 1
        ans = max(ans, max(temp))
    print(ans)

main()

Buggy python submission (verdict: Time Limit Exceeded):
import numpy as np

def main():
    H, W = map(int, input().split())
    S = [list(input()) for _ in range(H)]
    
    left = np.zeros([H, W], dtype=np.int) - 1
    right = np.zeros([H, W], dtype=np.int) - 1
    up = np.zeros([H, W], dtype=np.int) - 1
    down = np.zeros([H, W], dtype=np.int) - 1

    for i in range(H):
        for j in range(W):
            if S[i][j] == '.':
                if j == 0:
                    left[i][j] = 0
                else:
                    left[i][j] = left[i][j-1] + 1
                if i == 0:
                    up[i][j] = 0
                else:
                    up[i][j] = up[i-1][j] + 1
            
            if S[-1-i][-1-j] == '.':
                if j == 0:
                    right[-1-i][-1-j] = 0
                else:
                    right[-1-i][-1-j] = right[-1-i][-1-(j-1)] + 1
                if i == 0:
                    down[-1-i][-1-j] = 0
                else:
                    down[-1-i][-1-j] = down[-1-(i-1)][-1-j] + 1
                
    print(np.max(left+right+up+down) + 1)

main()

Fixed submission:
def main():
    H, W = map(int, input().split())
    S = [list(input()) for _ in range(H)]

    left = [[-1]*W for _ in range(H)]
    right = [[-1]*W for _ in range(H)]
    up = [[-1]*W for _ in range(H)]
    down = [[-1]*W for _ in range(H)]

    for i in range(H):
        for j in range(W):
            if S[i][j] == '.':
                if j == 0:
                    left[i][j] = 0
                else:
                    left[i][j] = left[i][j-1] + 1

    for i in range(H):
        for j in range(W):
            if S[-1-i][-1-j] == '.':        
                if j == 0:
                    right[-1-i][-1-j] = 0
                else:
                    right[-1-i][-1-j] = right[-1-i][-1-(j-1)] + 1

    for i in range(H):
        for j in range(W):
            if S[i][j] == '.':
                if i == 0:
                    up[i][j] = 0
                else:
                    up[i][j] = up[i-1][j] + 1

    for i in range(H):
        for j in range(W):
            if S[-1-i][-1-j] == '.':
                if i == 0:
                    down[-1-i][-1-j] = 0
                else:
                    down[-1-i][-1-j] = down[-1-(i-1)][-1-j] + 1
            
    ans = 0
    temp = [0] * W
    for i in range(H):
        for j in range(W):
            temp[j] = left[i][j] + right[i][j] + down[i][j] + up[i][j] + 1
        ans = max(ans, max(temp))
    print(ans)

main()

Buggy python submission (verdict: Time Limit Exceeded):
def main():
    H, W = map(int, input().split())
    S = [list(input()) for _ in range(H)]

    left = [[-1]*W for _ in range(H)]
    right = [[-1]*W for _ in range(H)]
    up = [[-1]*W for _ in range(H)]
    down = [[-1]*W for _ in range(H)]

    for i in range(H):
        for j in range(W):
            if S[i][j] == '.':
                if j == 0:
                    left[i][j] = 0
                else:
                    left[i][j] = left[i][j-1] + 1

    for i in range(H):
        for j in range(W):
            if S[-1-i][-1-j] == '.':        
                if j == 0:
                    right[-1-i][-1-j] = 0
                else:
                    right[-1-i][-1-j] = right[-1-i][-1-(j-1)] + 1

    for i in range(H):
        for j in range(W):
            if S[i][j] == '.':
                if i == 0:
                    up[i][j] = 0
                else:
                    up[i][j] = up[i-1][j] + 1

    for i in range(H):
        for j in range(W):
            if S[-1-i][-1-j] == '.':
                if i == 0:
                    down[-1-i][-1-j] = 0
                else:
                    down[-1-i][-1-j] = down[-1-(i-1)][-1-j] + 1
            
    ans = 0
    temp = [0] * W
    for i in range(H):
        for j in range(W):
            temp[j] = left[i][j] + right[i][j] + down[i][j] + up[i][j] + 1
        ans = max(ans, max(temp))
    print(ans)

main()

Fixed submission:
def main():
    H, W = map(int, input().split())
    S = [list(input()) for _ in range(H)]

    left = [[-1]*W for _ in range(H)]
    right = [[-1]*W for _ in range(H)]
    up = [[-1]*W for _ in range(H)]
    down = [[-1]*W for _ in range(H)]

    for i in range(H):
        for j in range(W):
            if S[i][j] == '.':
                if j == 0:
                    left[i][j] = 0
                else:
                    left[i][j] = left[i][j-1] + 1

    for i in range(H):
        for j in range(W):
            if S[-1-i][-1-j] == '.':        
                if j == 0:
                    right[-1-i][-1-j] = 0
                else:
                    right[-1-i][-1-j] = right[-1-i][-1-(j-1)] + 1

    for i in range(H):
        for j in range(W):
            if S[i][j] == '.':
                if i == 0:
                    up[i][j] = 0
                else:
                    up[i][j] = up[i-1][j] + 1

    for i in range(H):
        for j in range(W):
            if S[-1-i][-1-j] == '.':
                if i == 0:
                    down[-1-i][-1-j] = 0
                else:
                    down[-1-i][-1-j] = down[-1-(i-1)][-1-j] + 1
            
    ans = 0
    temp = [0] * W
    for i in range(H):
        for j in range(W):
            temp[j] = left[i][j] + right[i][j] + down[i][j] + up[i][j] + 1
        ans = max(ans, max(temp))
    print(ans)

main()

Buggy python submission (verdict: Runtime Error):
def main():
    H, W = map(int, input().split())
    S = [list(input()) for _ in range(H)]

    left = [[-1]*W for _ in range(H)]
    right = [[-1]*W for _ in range(H)]
    up = [[N]*W for _ in range(H)]
    down = [[None]*W for _ in range(H)]

    for i in range(H):
        for j in range(W):
            if S[i][j] == '.':
                if j == 0:
                    left[i][j] = 0
                else:
                    left[i][j] = left[i][j-1] + 1

    for i in range(H):
        for j in range(W):
            if S[-1-i][-1-j] == '.':        
                if j == 0:
                    right[-1-i][-1-j] = 0
                else:
                    right[-1-i][-1-j] = right[-1-i][-1-(j-1)] + 1

    for i in range(H):
        for j in range(W):
            if S[i][j] == '.':
                if i == 0:
                    up[i][j] = 0
                else:
                    up[i][j] = up[i-1][j] + 1

    for i in range(H):
        for j in range(W):
            if S[-1-i][-1-j] == '.':
                if i == 0:
                    down[-1-i][-1-j] = 0
                else:
                    down[-1-i][-1-j] = down[-1-(i-1)][-1-j] + 1
            
    ans = 0
    temp = [0] * W
    for i in range(H):
        for j in range(W):
            temp[j] = left[i][j] + right[i][j] + down[i][j] + up[i][j] + 1
        ans = max(ans, max(temp))
    print(ans)

main()

Fixed submission:
def main():
    H, W = map(int, input().split())
    S = [list(input()) for _ in range(H)]

    left = [[-1]*W for _ in range(H)]
    right = [[-1]*W for _ in range(H)]
    up = [[-1]*W for _ in range(H)]
    down = [[-1]*W for _ in range(H)]

    for i in range(H):
        for j in range(W):
            if S[i][j] == '.':
                if j == 0:
                    left[i][j] = 0
                else:
                    left[i][j] = left[i][j-1] + 1

    for i in range(H):
        for j in range(W):
            if S[-1-i][-1-j] == '.':        
                if j == 0:
                    right[-1-i][-1-j] = 0
                else:
                    right[-1-i][-1-j] = right[-1-i][-1-(j-1)] + 1

    for i in range(H):
        for j in range(W):
            if S[i][j] == '.':
                if i == 0:
                    up[i][j] = 0
                else:
                    up[i][j] = up[i-1][j] + 1

    for i in range(H):
        for j in range(W):
            if S[-1-i][-1-j] == '.':
                if i == 0:
                    down[-1-i][-1-j] = 0
                else:
                    down[-1-i][-1-j] = down[-1-(i-1)][-1-j] + 1
            
    ans = 0
    temp = [0] * W
    for i in range(H):
        for j in range(W):
            temp[j] = left[i][j] + right[i][j] + down[i][j] + up[i][j] + 1
        ans = max(ans, max(temp))
    print(ans)

main()

Buggy python submission (verdict: Time Limit Exceeded):
def main():
    H, W = map(int, input().split())
    S = [list(input()) for _ in range(H)]

    left = [[None]*W for _ in range(H)]
    right = [[None]*W for _ in range(H)]
    up = [[None]*W for _ in range(H)]
    down = [[None]*W for _ in range(H)]

    for i in range(H):
        for j in range(W):
            if S[i][j] == '.':
                if j == 0:
                    left[i][j] = 0
                else:
                    left[i][j] = left[i][j-1] + 1
            else:
                left[i][j] = -1

    for i in range(H):
        for j in range(W):
            if S[-1-i][-1-j] == '.':        
                if j == 0:
                    right[-1-i][-1-j] = 0
                else:
                    right[-1-i][-1-j] = right[-1-i][-1-(j-1)] + 1
            else:
                right[-1-i][-1-j] = -1

    for i in range(H):
        for j in range(W):
            if S[i][j] == '.':
                if i == 0:
                    up[i][j] = 0
                else:
                    up[i][j] = up[i-1][j] + 1
            else:
                up[i][j] = -1

    for i in range(H):
        for j in range(W):
            if S[-1-i][-1-j] == '.':
                if i == 0:
                    down[-1-i][-1-j] = 0
                else:
                    down[-1-i][-1-j] = down[-1-(i-1)][-1-j] + 1
            else:
                down[-1-i][-1-j] = -1
            
    ans = 0
    temp = [0] * W
    for i in range(H):
        for j in range(W):
            temp[j] = left[i][j] + right[i][j] + down[i][j] + up[i][j] + 1
        ans = max(ans, max(temp))
    print(ans)

main()

Fixed submission:
def main():
    H, W = map(int, input().split())
    S = [list(input()) for _ in range(H)]

    left = [[-1]*W for _ in range(H)]
    right = [[-1]*W for _ in range(H)]
    up = [[-1]*W for _ in range(H)]
    down = [[-1]*W for _ in range(H)]

    for i in range(H):
        for j in range(W):
            if S[i][j] == '.':
                if j == 0:
                    left[i][j] = 0
                else:
                    left[i][j] = left[i][j-1] + 1

    for i in range(H):
        for j in range(W):
            if S[-1-i][-1-j] == '.':        
                if j == 0:
                    right[-1-i][-1-j] = 0
                else:
                    right[-1-i][-1-j] = right[-1-i][-1-(j-1)] + 1

    for i in range(H):
        for j in range(W):
            if S[i][j] == '.':
                if i == 0:
                    up[i][j] = 0
                else:
                    up[i][j] = up[i-1][j] + 1

    for i in range(H):
        for j in range(W):
            if S[-1-i][-1-j] == '.':
                if i == 0:
                    down[-1-i][-1-j] = 0
                else:
                    down[-1-i][-1-j] = down[-1-(i-1)][-1-j] + 1
            
    ans = 0
    temp = [0] * W
    for i in range(H):
        for j in range(W):
            temp[j] = left[i][j] + right[i][j] + down[i][j] + up[i][j] + 1
        ans = max(ans, max(temp))
    print(ans)

main()

Buggy python submission (verdict: Time Limit Exceeded):
def main():
    H, W = map(int, input().split())
    S = [list(input()) for _ in range(H)]
    
    left = [[None]*W for _ in range(H)]
    right = [[None]*W for _ in range(H)]
    up = [[None]*W for _ in range(H)]
    down = [[None]*W for _ in range(H)]

    for i in range(H):
        for j in range(W):
            if S[i][j] == '.':
                if j == 0:
                    left[i][j] = 0
                else:
                    left[i][j] = left[i][j-1] + 1
                if i == 0:
                    up[i][j] = 0
                else:
                    up[i][j] = up[i-1][j] + 1
            else:
                left[i][j] = -1
                up[i][j] = -1
            
            if S[-1-i][-1-j] == '.':
                if j == 0:
                    right[-1-i][-1-j] = 0
                else:
                    right[-1-i][-1-j] = right[-1-i][-1-(j-1)] + 1
                if i == 0:
                    down[-1-i][-1-j] = 0
                else:
                    down[-1-i][-1-j] = down[-1-(i-1)][-1-j] + 1
            else:
                right[-1-i][-1-j] = -1
                down[-1-i][-1-j] = -1

    ans = 0
    temp = [0] * W
    for i in range(H):
        for j in range(W):
            temp[j] = left[i][j] + right[i][j] + down[i][j] + up[i][j] + 1
        ans = max(ans, max(temp))
    print(ans)

main()

Fixed submission:
def main():
    H, W = map(int, input().split())
    S = [list(input()) for _ in range(H)]

    left = [[-1]*W for _ in range(H)]
    right = [[-1]*W for _ in range(H)]
    up = [[-1]*W for _ in range(H)]
    down = [[-1]*W for _ in range(H)]

    for i in range(H):
        for j in range(W):
            if S[i][j] == '.':
                if j == 0:
                    left[i][j] = 0
                else:
                    left[i][j] = left[i][j-1] + 1

    for i in range(H):
        for j in range(W):
            if S[-1-i][-1-j] == '.':        
                if j == 0:
                    right[-1-i][-1-j] = 0
                else:
                    right[-1-i][-1-j] = right[-1-i][-1-(j-1)] + 1

    for i in range(H):
        for j in range(W):
            if S[i][j] == '.':
                if i == 0:
                    up[i][j] = 0
                else:
                    up[i][j] = up[i-1][j] + 1

    for i in range(H):
        for j in range(W):
            if S[-1-i][-1-j] == '.':
                if i == 0:
                    down[-1-i][-1-j] = 0
                else:
                    down[-1-i][-1-j] = down[-1-(i-1)][-1-j] + 1
            
    ans = 0
    temp = [0] * W
    for i in range(H):
        for j in range(W):
            temp[j] = left[i][j] + right[i][j] + down[i][j] + up[i][j] + 1
        ans = max(ans, max(temp))
    print(ans)

main()

Buggy python submission (verdict: Runtime Error):
def main():
    left = [[None]*W]*H
    right = [[None]*W]*H
    up = [[None]*W]*H
    down = [[None]*W]*H

    for i in range(H):
        for j in range(W):
            if S[i][j] == '.':
                if j == 0:
                    left[i][j] = 0
                else:
                    left[i][j] = left[i][j-1] + 1
                if i == 0:
                    up[i][j] = 0
                else:
                    up[i][j] = up[i-1][j] + 1
            else:
                left[i][j] = -1
                up[i][j] = -1
            
            if S[-1-i][-1-j] == '.':
                if j == 0:
                    right[-1-i][-1-j] = 0
                else:
                    right[-1-i][-1-j] = right[-1-i][-1-(j-1)] + 1
                if i == 0:
                    down[-1-i][-1-j] = 0
                else:
                    down[-1-i][-1-j] = down[-1-(i-1)][-1-j] + 1
            else:
                right[-1-i][-1-j] = -1
                down[-1-i][-1-j] = -1

    ans = 0
    for i in range(H):
        for j in range(W):
            ans = max(ans, left[i][j]+right[i][j]+up[i][j]+down[i][j])
    print(ans+1)
    
main()

Fixed submission:
def main():
    H, W = map(int, input().split())
    S = [list(input()) for _ in range(H)]

    left = [[-1]*W for _ in range(H)]
    right = [[-1]*W for _ in range(H)]
    up = [[-1]*W for _ in range(H)]
    down = [[-1]*W for _ in range(H)]

    for i in range(H):
        for j in range(W):
            if S[i][j] == '.':
                if j == 0:
                    left[i][j] = 0
                else:
                    left[i][j] = left[i][j-1] + 1

    for i in range(H):
        for j in range(W):
            if S[-1-i][-1-j] == '.':        
                if j == 0:
                    right[-1-i][-1-j] = 0
                else:
                    right[-1-i][-1-j] = right[-1-i][-1-(j-1)] + 1

    for i in range(H):
        for j in range(W):
            if S[i][j] == '.':
                if i == 0:
                    up[i][j] = 0
                else:
                    up[i][j] = up[i-1][j] + 1

    for i in range(H):
        for j in range(W):
            if S[-1-i][-1-j] == '.':
                if i == 0:
                    down[-1-i][-1-j] = 0
                else:
                    down[-1-i][-1-j] = down[-1-(i-1)][-1-j] + 1
            
    ans = 0
    temp = [0] * W
    for i in range(H):
        for j in range(W):
            temp[j] = left[i][j] + right[i][j] + down[i][j] + up[i][j] + 1
        ans = max(ans, max(temp))
    print(ans)

main()

Buggy python submission (verdict: Time Limit Exceeded):
import numpy as np

def main():
    H, W = map(int, input().split())
    S = [list(input()) for _ in range(H)]
    
    left = np.zeros([H, W], dtype=np.int)
    right = np.zeros([H, W], dtype=np.int)
    up = np.zeros([H, W], dtype=np.int)
    down = np.zeros([H, W], dtype=np.int)

    for i in range(H):
        for j in range(W):
            if S[i][j] == '.':
                if j == 0:
                    left[i][j] = 0
                else:
                    left[i][j] = left[i][j-1] + 1
                if i == 0:
                    up[i][j] = 0
                else:
                    up[i][j] = up[i-1][j] + 1
            else:
                left[i][j] = -1
                up[i][j] = -1
            
            if S[-1-i][-1-j] == '.':
                if j == 0:
                    right[-1-i][-1-j] = 0
                else:
                    right[-1-i][-1-j] = right[-1-i][-1-(j-1)] + 1
                if i == 0:
                    down[-1-i][-1-j] = 0
                else:
                    down[-1-i][-1-j] = down[-1-(i-1)][-1-j] + 1
            else:
                right[-1-i][-1-j] = -1
                down[-1-i][-1-j] = -1
                
    print(np.max(left+right+up+down) + 1)

main()

Fixed submission:
def main():
    H, W = map(int, input().split())
    S = [list(input()) for _ in range(H)]

    left = [[-1]*W for _ in range(H)]
    right = [[-1]*W for _ in range(H)]
    up = [[-1]*W for _ in range(H)]
    down = [[-1]*W for _ in range(H)]

    for i in range(H):
        for j in range(W):
            if S[i][j] == '.':
                if j == 0:
                    left[i][j] = 0
                else:
                    left[i][j] = left[i][j-1] + 1

    for i in range(H):
        for j in range(W):
            if S[-1-i][-1-j] == '.':        
                if j == 0:
                    right[-1-i][-1-j] = 0
                else:
                    right[-1-i][-1-j] = right[-1-i][-1-(j-1)] + 1

    for i in range(H):
        for j in range(W):
            if S[i][j] == '.':
                if i == 0:
                    up[i][j] = 0
                else:
                    up[i][j] = up[i-1][j] + 1

    for i in range(H):
        for j in range(W):
            if S[-1-i][-1-j] == '.':
                if i == 0:
                    down[-1-i][-1-j] = 0
                else:
                    down[-1-i][-1-j] = down[-1-(i-1)][-1-j] + 1
            
    ans = 0
    temp = [0] * W
    for i in range(H):
        for j in range(W):
            temp[j] = left[i][j] + right[i][j] + down[i][j] + up[i][j] + 1
        ans = max(ans, max(temp))
    print(ans)

main()

Buggy python submission (verdict: Runtime Error):
def main():
    H, W = map(int, input().split())
    S = [list(input()) for _ in range(H)]
    
    left = [[-1]*W]*H
    right = [[-1]*W]*H
    up = [[-1]*W]*H
    down = [[-1]*W]*H

    for i in range(H):
        for j in range(W):
            if S[i][j] == '.':
                if j == 0:
                    left[i][j] = 0
                else:
                    left[i][j] = left[i][j-1] + 1
                if i == 0:
                    up[i][j] = 0
                else:
                    up[i][j] = up[i-1][j] + 1
            else:
                left[i][j] = -1
                up[i][j] = -1
            
            if S[-1-i][-1-j] == '.':
                if j == 0:
                    right[-1-i][-1-j] = 0
                else:
                    right[-1-i][-1-j] = right[-1-i][-1-(j-1)] + 1
                if i == 0:
                    down[-1-i][-1-j] = 0
                else:
                    down[-1-i][-1-j] = down[-1-(i-1)][-1-j] + 1
            else:
                right[i][j] = -1
                down[i][j] = -1
                
    print(np.max(left+right+up+down) + 1)

main()

Fixed submission:
def main():
    H, W = map(int, input().split())
    S = [list(input()) for _ in range(H)]

    left = [[-1]*W for _ in range(H)]
    right = [[-1]*W for _ in range(H)]
    up = [[-1]*W for _ in range(H)]
    down = [[-1]*W for _ in range(H)]

    for i in range(H):
        for j in range(W):
            if S[i][j] == '.':
                if j == 0:
                    left[i][j] = 0
                else:
                    left[i][j] = left[i][j-1] + 1

    for i in range(H):
        for j in range(W):
            if S[-1-i][-1-j] == '.':        
                if j == 0:
                    right[-1-i][-1-j] = 0
                else:
                    right[-1-i][-1-j] = right[-1-i][-1-(j-1)] + 1

    for i in range(H):
        for j in range(W):
            if S[i][j] == '.':
                if i == 0:
                    up[i][j] = 0
                else:
                    up[i][j] = up[i-1][j] + 1

    for i in range(H):
        for j in range(W):
            if S[-1-i][-1-j] == '.':
                if i == 0:
                    down[-1-i][-1-j] = 0
                else:
                    down[-1-i][-1-j] = down[-1-(i-1)][-1-j] + 1
            
    ans = 0
    temp = [0] * W
    for i in range(H):
        for j in range(W):
            temp[j] = left[i][j] + right[i][j] + down[i][j] + up[i][j] + 1
        ans = max(ans, max(temp))
    print(ans)

main()

Buggy python submission (verdict: Runtime Error):
import numpy as np

def main():
    H, W = map(int, input().split())
    S = [list(input()) for _ in range(H)]
    
    left = np.zeros([H, W], dtype=np.int) - 1
    right = np.zeros([H, W], dtype=np.int) - 1
    up = np.zeros([H, W], dtype=np.int) - 1
    down = np.zeros([H, W], dtype=np.int) - 1

    for i in range(H):
        for j in range(W):
            if S[i][j] == '.':
                if j == 0:
                    left[i][j] = 0
                else:
                    left[i][j] = left[i][j-1] + 1
                if i == 0:
                    up[i][j] = 0
                else:
                    up[i][j] = up[i-1][j] + 1
            else:
                left[i][j] = -1
                up[i][j] = -1
            
            if S[-1-i][-1-j] == '.':
                if j == 0:
                    right[-1-i][-1-j] = 0
                else:
                    right[-1-i][-1-j] = right[-1-i][-1-(j-1)] + 1
                if i == 0:
                    down[-1-i][-1-j] = 0
                else:
                    down[-1-i][-1-j] = down[-1-(i-1)][-1-j] + 1
            else:
                right[i][j] = -1
                down[i][j] = -1
                
    print(np.max(left+right+up+down) + 1)

main()

Fixed submission:
def main():
    H, W = map(int, input().split())
    S = [list(input()) for _ in range(H)]

    left = [[-1]*W for _ in range(H)]
    right = [[-1]*W for _ in range(H)]
    up = [[-1]*W for _ in range(H)]
    down = [[-1]*W for _ in range(H)]

    for i in range(H):
        for j in range(W):
            if S[i][j] == '.':
                if j == 0:
                    left[i][j] = 0
                else:
                    left[i][j] = left[i][j-1] + 1

    for i in range(H):
        for j in range(W):
            if S[-1-i][-1-j] == '.':        
                if j == 0:
                    right[-1-i][-1-j] = 0
                else:
                    right[-1-i][-1-j] = right[-1-i][-1-(j-1)] + 1

    for i in range(H):
        for j in range(W):
            if S[i][j] == '.':
                if i == 0:
                    up[i][j] = 0
                else:
                    up[i][j] = up[i-1][j] + 1

    for i in range(H):
        for j in range(W):
            if S[-1-i][-1-j] == '.':
                if i == 0:
                    down[-1-i][-1-j] = 0
                else:
                    down[-1-i][-1-j] = down[-1-(i-1)][-1-j] + 1
            
    ans = 0
    temp = [0] * W
    for i in range(H):
        for j in range(W):
            temp[j] = left[i][j] + right[i][j] + down[i][j] + up[i][j] + 1
        ans = max(ans, max(temp))
    print(ans)

main()