Buggy python submission (verdict: Time Limit Exceeded):
H, W = map(int, input().split())
S = ""
for i in range(H):
    S += input()

vert = [0] * (H*W)
horz = [0] * (H*W)

for i in range(H*W):
    if S[i] == '.':
        if i - W >= 0:
            if S[i - W] == '.':
                vert[i] = vert[i - W]
                continue
        j = i
        L = 0
        while S[j] == '.':
            L += 1
            j += W
            if j >= H * W:
                break
        vert[i] = L

for i in range(H*W):
    if S[i] == '.':
        if i % W > 0:
            if S[i - 1] == '.':
                horz[i] = horz[i - 1]
                continue
        j = i
        L = 0
        while S[j] == '.':
            L += 1
            j += 1
            if j % W == 0:
                break
        horz[i] = L

light = [0] * (H*W)
for i in range(H * W):
    light[i] = horz[i] + vert[i]
print(max(light) - 1)


Fixed submission:
def main():
    import sys
    input = sys.stdin.readline

    H, W = map(int, input().split())
    grid = []
    for _ in range(H):
        grid.append(input().rstrip('\n'))

    L = [[0] * W for _ in range(H)]
    R = [[0] * W for _ in range(H)]
    U = [[0] * W for _ in range(H)]
    D = [[0] * W for _ in range(H)]
    for h in range(H):
        for w in range(1, W):
            if grid[h][w-1] == '.' and grid[h][w] == '.':
                L[h][w] = L[h][w-1] + 1
    for h in range(H):
        for w in range(W-2, -1, -1):
            if grid[h][w] == '.' and grid[h][w+1] == '.':
                R[h][w] = R[h][w+1] + 1
    for w in range(W):
        for h in range(1, H):
            if grid[h][w] == '.' and grid[h-1][w] == '.':
                U[h][w] = U[h-1][w] + 1
    for w in range(W):
        for h in range(H-2, -1, -1):
            if grid[h][w] == '.' and grid[h+1][w] == '.':
                D[h][w] = D[h+1][w] + 1

    ans = 1
    for h in range(H):
        for w in range(W):
            ans = max(ans, L[h][w] + R[h][w] + U[h][w] + D[h][w] + 1)
    print(ans)


if __name__ == '__main__':
    main()

Buggy python submission (verdict: Time Limit Exceeded):
H, W = map(int, input().split())
S = ""
for i in range(H):
    S += input()

vert = [0] * (H*W)
horz = [0] * (H*W)

for i in range(H*W):
    if S[i] == '.':
        if i - W >= 0:
            if S[i - W] == '.':
                vert[i] = vert[i - W]
                continue
        j = i
        L = 0
        while True:
            if j >= H * W:
                vert[i] = L
                break
            if S[j] == '.':
                L += 1
            else:
                vert[i] = L
                break
            j += W

for i in range(H*W):
    if S[i] == '.':
        if i % W > 0:
            if S[i - 1] == '.':
                horz[i] = horz[i - 1]
                continue
        j = i
        L = 0
        while True:
            if S[j] == '.':
                L += 1
            else:
                horz[i] = L
                break
            j += 1
            if j % W == 0:
                horz[i] = L
                break

light = [0] * (H*W)
for i in range(H * W):
    light[i] = horz[i] + vert[i]
print(max(light) - 1)


Fixed submission:
def main():
    import sys
    input = sys.stdin.readline

    H, W = map(int, input().split())
    grid = []
    for _ in range(H):
        grid.append(input().rstrip('\n'))

    L = [[0] * W for _ in range(H)]
    R = [[0] * W for _ in range(H)]
    U = [[0] * W for _ in range(H)]
    D = [[0] * W for _ in range(H)]
    for h in range(H):
        for w in range(1, W):
            if grid[h][w-1] == '.' and grid[h][w] == '.':
                L[h][w] = L[h][w-1] + 1
    for h in range(H):
        for w in range(W-2, -1, -1):
            if grid[h][w] == '.' and grid[h][w+1] == '.':
                R[h][w] = R[h][w+1] + 1
    for w in range(W):
        for h in range(1, H):
            if grid[h][w] == '.' and grid[h-1][w] == '.':
                U[h][w] = U[h-1][w] + 1
    for w in range(W):
        for h in range(H-2, -1, -1):
            if grid[h][w] == '.' and grid[h+1][w] == '.':
                D[h][w] = D[h+1][w] + 1

    ans = 1
    for h in range(H):
        for w in range(W):
            ans = max(ans, L[h][w] + R[h][w] + U[h][w] + D[h][w] + 1)
    print(ans)


if __name__ == '__main__':
    main()

Buggy python submission (verdict: Time Limit Exceeded):
H, W = map(int, input().split())
S = ""
for i in range(H):
    S += input()

vert = [0] * (H*W)
horz = [0] * (H*W)

for i in range(H*W):
    if S[i] == '.':
        if i - W >= 0:
            if S[i - W] == '.':
                vert[i] = vert[i - W]
                continue
        j = i
        while True:
            if j >= H * W:
                break
            if S[j] == '.':
                vert[i] += 1
            else:
                break
            j += W

for i in range(H*W):
    if S[i] == '.':
        if i % W > 0:
            if S[i - 1] == '.':
                horz[i] = horz[i - 1]
                continue
        j = i
        while True:
            if S[j] == '.':
                horz[i] += 1
            else:
                break
            j += 1
            if j % W == 0:
                break

light = [0] * (H*W)
for i in range(H * W):
    light[i] = horz[i] + vert[i]
print(max(light) - 1)


Fixed submission:
def main():
    import sys
    input = sys.stdin.readline

    H, W = map(int, input().split())
    grid = []
    for _ in range(H):
        grid.append(input().rstrip('\n'))

    L = [[0] * W for _ in range(H)]
    R = [[0] * W for _ in range(H)]
    U = [[0] * W for _ in range(H)]
    D = [[0] * W for _ in range(H)]
    for h in range(H):
        for w in range(1, W):
            if grid[h][w-1] == '.' and grid[h][w] == '.':
                L[h][w] = L[h][w-1] + 1
    for h in range(H):
        for w in range(W-2, -1, -1):
            if grid[h][w] == '.' and grid[h][w+1] == '.':
                R[h][w] = R[h][w+1] + 1
    for w in range(W):
        for h in range(1, H):
            if grid[h][w] == '.' and grid[h-1][w] == '.':
                U[h][w] = U[h-1][w] + 1
    for w in range(W):
        for h in range(H-2, -1, -1):
            if grid[h][w] == '.' and grid[h+1][w] == '.':
                D[h][w] = D[h+1][w] + 1

    ans = 1
    for h in range(H):
        for w in range(W):
            ans = max(ans, L[h][w] + R[h][w] + U[h][w] + D[h][w] + 1)
    print(ans)


if __name__ == '__main__':
    main()

Buggy python submission (verdict: Runtime Error):
H, W = map(int, input().split())
S = ""
for i in range(H):
    S += input()

light = [0] * (H*W)
for h in range(H):
    cnt = 0
    pre = "@"
    info = []
    for i in range(h*W, (h+1)*W):
        if S[i] == pre:
            cnt += 1
            if i == (h+1)*W-1:
                if S[i] == ".":
                    info.append(cnt)
                else:
                    info.append(-cnt)
        else:
            if pre == ".":
                info.append(cnt)
                cnt = 1
            elif pre == "#":
                info.append(-cnt)
                cnt = 1
    cnt = h*W
    while len(info) > 0:
        LD = info.pop(0)
        if LD > 0: 
            for i in range(LD):
                light[cnt + i] += LD
            cnt += LD
        else:
            for i in range(-LD):
                light[cnt + i] = 0
            cnt += -LD

for w in range(W):
    cnt = 0
    pre = "@"
    info = []
    for i in range(H):
        if S[w + i * H] == pre:
            cnt += 1
            if i == H-1:
                if S[w + i * H] == ".":
                    info.append(cnt)
                else:
                    info.append(-cnt)
        else:
            if pre == ".":
                info.append(cnt)
                cnt = 1
            elif pre == "#":
                info.append(-cnt)
                cnt = 1
    cnt = w
    while len(info) > 0:
        LD = info.pop(0)
        if LD > 0: 
            for i in range(LD):
                light[w + i * H] += LD
            cnt += LD * H
        else:
            for i in range(-LD):
                light[i] = 0
            cnt += -LD * H
print(max(light)-1)

Fixed submission:
def main():
    import sys
    input = sys.stdin.readline

    H, W = map(int, input().split())
    grid = []
    for _ in range(H):
        grid.append(input().rstrip('\n'))

    L = [[0] * W for _ in range(H)]
    R = [[0] * W for _ in range(H)]
    U = [[0] * W for _ in range(H)]
    D = [[0] * W for _ in range(H)]
    for h in range(H):
        for w in range(1, W):
            if grid[h][w-1] == '.' and grid[h][w] == '.':
                L[h][w] = L[h][w-1] + 1
    for h in range(H):
        for w in range(W-2, -1, -1):
            if grid[h][w] == '.' and grid[h][w+1] == '.':
                R[h][w] = R[h][w+1] + 1
    for w in range(W):
        for h in range(1, H):
            if grid[h][w] == '.' and grid[h-1][w] == '.':
                U[h][w] = U[h-1][w] + 1
    for w in range(W):
        for h in range(H-2, -1, -1):
            if grid[h][w] == '.' and grid[h+1][w] == '.':
                D[h][w] = D[h+1][w] + 1

    ans = 1
    for h in range(H):
        for w in range(W):
            ans = max(ans, L[h][w] + R[h][w] + U[h][w] + D[h][w] + 1)
    print(ans)


if __name__ == '__main__':
    main()

Buggy python submission (verdict: Time Limit Exceeded):
H, W = map(int, input().split())
S = ""
for i in range(H):
    S += input()

vert = [0] * (H*W)
horz = [0] * (H*W)

for i in range(H*W):
    if S[i] == '.':
        if i - W >= 0:
            if S[i - W] == '.':
                vert[i] = vert[i - W]
                continue
        j = i
        while True:
            if j >= H * W:
                break
            if S[j] == '.':
                vert[i] += 1
            else:
                break
            j += W

for i in range(H*W):
    if S[i] == '.':
        if i % W > 0:
            if S[i - 1] == '.':
                horz[i] = horz[i - 1]
                continue
        j = i
        while True:
            if S[j] == '.':
                horz[i] += 1
            else:
                break
            j += 1
            if j % W == 0:
                break

light = [0] * (H*W)
for i in range(H * W):
    light[i] = horz[i] + vert[i]
print(max(light) - 1)


Fixed submission:
def main():
    import sys
    input = sys.stdin.readline

    H, W = map(int, input().split())
    grid = []
    for _ in range(H):
        grid.append(input().rstrip('\n'))

    L = [[0] * W for _ in range(H)]
    R = [[0] * W for _ in range(H)]
    U = [[0] * W for _ in range(H)]
    D = [[0] * W for _ in range(H)]
    for h in range(H):
        for w in range(1, W):
            if grid[h][w-1] == '.' and grid[h][w] == '.':
                L[h][w] = L[h][w-1] + 1
    for h in range(H):
        for w in range(W-2, -1, -1):
            if grid[h][w] == '.' and grid[h][w+1] == '.':
                R[h][w] = R[h][w+1] + 1
    for w in range(W):
        for h in range(1, H):
            if grid[h][w] == '.' and grid[h-1][w] == '.':
                U[h][w] = U[h-1][w] + 1
    for w in range(W):
        for h in range(H-2, -1, -1):
            if grid[h][w] == '.' and grid[h+1][w] == '.':
                D[h][w] = D[h+1][w] + 1

    ans = 1
    for h in range(H):
        for w in range(W):
            ans = max(ans, L[h][w] + R[h][w] + U[h][w] + D[h][w] + 1)
    print(ans)


if __name__ == '__main__':
    main()