Buggy python submission (verdict: Runtime Error):
def solve():
    h, w = map(int, input().split())
    S = list(input() + '#' for _ in range(h)) + ['#' * (w + 1)]
    H = [[0] * w for _ in range(h + 1)]
    W = [[0] * w for _ in range(h + 1)]
    def f(r, c, num):
        if W[r][c] == 0:
            if c < w and S[r][c + 1] == '.':
                W[r][c] = f(r, c + 1, num + 1)
            else:
                W[r][c] = num
        return W[r][c]
    def g(r, c, num):
        if H[r][c] == 0:
            if r < h and S[r + 1][c] == '.':
                H[r][c] = g(r + 1, c, num + 1)
            else:
                H[r][c] = num
        return H[r][c]
    ans = 0
    for r in range(h):
        for c in range(w):
            if S[r][c] == '.':
                ans = max(ans, f(r, c, 1) + g(r, c, 1) - 1)
    print(ans)
solve()

Fixed submission:
def solve():
    h, w = map(int, input().split())
    S = list(input() + '#' for _ in range(h)) + ['#' * (w + 1)]
    H = [[0] * w for _ in range(h + 1)]
    W = [[0] * w for _ in range(h + 1)]
    for r in range(h):
        c = 0
        while c < w:
            if S[r][c] == '.':
                t = S[r][c:].find('#')
                for j in range(c, c + t):
                    W[r][j] = t
                c += t
            c += 1
    for c in range(w):
        r = 0
        while r < h:
            if S[r][c] == '.':
                t = r + 1
                cnt = 1
                while S[t][c] == '.':
                    t += 1
                    cnt += 1
                for i in range(r, t):
                    H[i][c] = cnt
                r = t
            r += 1
    ans = 0
    for r in range(h):
        for c in range(w):
            ans = max(ans, H[r][c] + W[r][c] - 1)
    print(ans)
solve()

Buggy python submission (verdict: Time Limit Exceeded):
import numpy as np
def solve():
    h, w = map(int, input().split())
    S = list(input() + '#' for _ in range(h)) + ['#' * (w + 1)]
    H = np.zeros([h + 1, w], dtype=np.int)
    W = np.zeros([h + 1, w], dtype=np.int)
    for r in range(h):
        c = 0
        while c < w:
            if S[r][c] == '.':
                t = S[r][c:].find('#')
                for j in range(c, c + t):
                    W[r][j] = t
                c += t
            c += 1
    for c in range(w):
        r = 0
        while r < h:
            if S[r][c] == '.':
                t = r + 1
                cnt = 1
                while S[t][c] == '.':
                    t += 1
                    cnt += 1
                for i in range(r, t):
                    H[i][c] = cnt
                r = t
            r += 1
    ans = 0
    for r in range(h):
        for c in range(w):
            ans = max(ans, H[r][c] + W[r][c] - 1)
    print(ans)
solve()


Fixed submission:
def solve():
    h, w = map(int, input().split())
    S = list(input() + '#' for _ in range(h)) + ['#' * (w + 1)]
    H = [[0] * w for _ in range(h + 1)]
    W = [[0] * w for _ in range(h + 1)]
    for r in range(h):
        c = 0
        while c < w:
            if S[r][c] == '.':
                t = S[r][c:].find('#')
                for j in range(c, c + t):
                    W[r][j] = t
                c += t
            c += 1
    for c in range(w):
        r = 0
        while r < h:
            if S[r][c] == '.':
                t = r + 1
                cnt = 1
                while S[t][c] == '.':
                    t += 1
                    cnt += 1
                for i in range(r, t):
                    H[i][c] = cnt
                r = t
            r += 1
    ans = 0
    for r in range(h):
        for c in range(w):
            ans = max(ans, H[r][c] + W[r][c] - 1)
    print(ans)
solve()

Buggy python submission (verdict: Runtime Error):
def solve():
    h, w = map(int, input().split())
    S = list(input() + '#' for _ in range(h)) + ['#' * (w + 1)]
    H = [[0] * w for _ in range(h + 1)]
    W = [[0] * w for _ in range(h + 1)]
    def f(r, c, num):
        if W[r][c] == 0:
            if c < w and S[r][c + 1] == '.':
                W[r][c] = f(r, c + 1, num + 1)
            else:
                W[r][c] = num
        return W[r][c]
    def g(r, c, num):
        if H[r][c] == 0:
            if r < h and S[r + 1][c] == '.':
                H[r][c] = g(r + 1, c, num + 1)
            else:
                H[r][c] = num
        return H[r][c]
    ans = 0
    for r in range(h):
        for c in range(w):
            if S[r][c] == '.':
                ans = max(ans, f(r, c, 1) + g(r, c, 1) - 1)
    print(ans)
solve()


Fixed submission:
def solve():
    h, w = map(int, input().split())
    S = list(input() + '#' for _ in range(h)) + ['#' * (w + 1)]
    H = [[0] * w for _ in range(h + 1)]
    W = [[0] * w for _ in range(h + 1)]
    for r in range(h):
        c = 0
        while c < w:
            if S[r][c] == '.':
                t = S[r][c:].find('#')
                for j in range(c, c + t):
                    W[r][j] = t
                c += t
            c += 1
    for c in range(w):
        r = 0
        while r < h:
            if S[r][c] == '.':
                t = r + 1
                cnt = 1
                while S[t][c] == '.':
                    t += 1
                    cnt += 1
                for i in range(r, t):
                    H[i][c] = cnt
                r = t
            r += 1
    ans = 0
    for r in range(h):
        for c in range(w):
            ans = max(ans, H[r][c] + W[r][c] - 1)
    print(ans)
solve()

Buggy python submission (verdict: Time Limit Exceeded):
def solve():
    h, w = map(int, input().split())
    S = list(input() + '#' for _ in range(h)) + ['#' * (w + 1)]
    H = [[0] * w for _ in range(h + 1)]
    W = [[0] * w for _ in range(h + 1)]
    for r in range(h):
        c = 0
        while c < w:
            if S[r][c] == '.':
                t = S[r][c:].find('#')
                for j in range(c, c + t):
                    W[r][j] = t
                c += t
            c += 1
    for c in range(w):
        r = 0
        while r < h:
            if S[r][c] == '.':
                t = r + 1
                cnt = 1
                while S[t][c] == '.':
                    t += 1
                    cnt += 1
                for i in range(r, t):
                    H[i][c] = cnt
                r = t
            r += 1
    ans = 0
    for r in range(h):
        for c in range(w):
            ans = max(ans, H[r][c] + W[r][c] - 1)
    print(ans)
solve()


Fixed submission:
def solve():
    h, w = map(int, input().split())
    S = list(input() + '#' for _ in range(h)) + ['#' * (w + 1)]
    H = [[0] * w for _ in range(h + 1)]
    W = [[0] * w for _ in range(h + 1)]
    for r in range(h):
        c = 0
        while c < w:
            if S[r][c] == '.':
                t = S[r][c:].find('#')
                for j in range(c, c + t):
                    W[r][j] = t
                c += t
            c += 1
    for c in range(w):
        r = 0
        while r < h:
            if S[r][c] == '.':
                t = r + 1
                cnt = 1
                while S[t][c] == '.':
                    t += 1
                    cnt += 1
                for i in range(r, t):
                    H[i][c] = cnt
                r = t
            r += 1
    ans = 0
    for r in range(h):
        for c in range(w):
            ans = max(ans, H[r][c] + W[r][c] - 1)
    print(ans)
solve()