Buggy python submission (verdict: Time Limit Exceeded):
from collections import deque


def bfs(S):  # 幅優先探索  # キュー
    dist = [-1] * (w * h)  # 前処理
    que = deque()
    for i, Si in enumerate(S):
        for j, Sij in enumerate(Si):
            if Sij == '#':
                dist[j + (w * i)] = 0
                que.append((i, j))

    while len(que) > 0:
        (x, y) = que.popleft()
        near = [(x + 1, y), (x - 1, y), (x, y + 1), (x, y - 1)]
        for i, j in near:  # 移動先の候補
            if 0 <= i < h and 0 <= j < w and dist[j + (w * i)] < 0:
                dist[j + (w * i)] = dist[y + (w * x)] + 1
                que.append((i, j))
    return max(dist)


h, w = map(int, input().split())
a = [input() for _ in range(h)]
print(bfs(a))


Fixed submission:
from collections import deque


def bfs(S):  # 幅優先探索  # キュー
    dist = [[-1] * w for _ in range(h)]  # 前処理
    que = deque()
    for i, Si in enumerate(S):
        for j, Sij in enumerate(Si):
            if Sij == '#':
                dist[i][j] = 0
                que.append((i, j))

    while len(que) > 0:
        (x, y) = que.popleft()
        near = [(x + 1, y), (x - 1, y), (x, y + 1), (x, y - 1)]
        for i, j in near:  # 移動先の候補
            if 0 <= i < h and 0 <= j < w and dist[i][j] < 0:
                dist[i][j] = dist[x][y] + 1
                que.append((i, j))
    return dist[x][y]


h, w = map(int, input().split())
a = [input() for _ in range(h)]
print(bfs(a))

Buggy python submission (verdict: Runtime Error):
from collections import deque


def bfs(S):  # 幅優先探索  # キュー
    dist = [-1] * (w * h)  # 前処理
    que = deque()
    for i, Si in enumerate(S):
        for j, Sij in enumerate(Si):
            if Sij == '#':
                dist[i + (w * j)] = 0
                que.append((i, j))

    while len(que) > 0:
        (x, y) = que.popleft()
        near = [(x + 1, y), (x - 1, y), (x, y + 1), (x, y - 1)]
        for i, j in near:  # 移動先の候補
            if 0 <= i < h and 0 <= j < w and dist[i + (w * j)] < 0:
                dist[i + (w * j)] = dist[x + (w * y)] + 1
                que.append((i, j))
    return dist[x + (w * y)]


h, w = map(int, input().split())
a = [input() for _ in range(h)]
print(bfs(a))


Fixed submission:
from collections import deque


def bfs(S):  # 幅優先探索  # キュー
    dist = [[-1] * w for _ in range(h)]  # 前処理
    que = deque()
    for i, Si in enumerate(S):
        for j, Sij in enumerate(Si):
            if Sij == '#':
                dist[i][j] = 0
                que.append((i, j))

    while len(que) > 0:
        (x, y) = que.popleft()
        near = [(x + 1, y), (x - 1, y), (x, y + 1), (x, y - 1)]
        for i, j in near:  # 移動先の候補
            if 0 <= i < h and 0 <= j < w and dist[i][j] < 0:
                dist[i][j] = dist[x][y] + 1
                que.append((i, j))
    return dist[x][y]


h, w = map(int, input().split())
a = [input() for _ in range(h)]
print(bfs(a))

Buggy python submission (verdict: Runtime Error):
from collections import deque


def bfs(S):  # 幅優先探索  # キュー
    dist = [-1] * (w * h)  # 前処理
    que = deque()
    for i, Si in enumerate(S):
        for j, Sij in enumerate(Si):
            if Sij == '#':
                dist[i + (w * j)] = 0
                que.append((i, j))

    while len(que) > 0:
        (x, y) = que.popleft()
        near = [(x + 1, y), (x - 1, y), (x, y + 1), (x, y - 1)]
        for i, j in near:  # 移動先の候補
            if 0 <= i < h and 0 <= j < w and dist[i][j] < 0:
                dist[i + (w * j)] = dist[x + (w * y)] + 1
                que.append((i, j))
    return dist[x + (w * y)]


h, w = map(int, input().split())
a = [input() for _ in range(h)]
print(bfs(a))


Fixed submission:
from collections import deque


def bfs(S):  # 幅優先探索  # キュー
    dist = [[-1] * w for _ in range(h)]  # 前処理
    que = deque()
    for i, Si in enumerate(S):
        for j, Sij in enumerate(Si):
            if Sij == '#':
                dist[i][j] = 0
                que.append((i, j))

    while len(que) > 0:
        (x, y) = que.popleft()
        near = [(x + 1, y), (x - 1, y), (x, y + 1), (x, y - 1)]
        for i, j in near:  # 移動先の候補
            if 0 <= i < h and 0 <= j < w and dist[i][j] < 0:
                dist[i][j] = dist[x][y] + 1
                que.append((i, j))
    return dist[x][y]


h, w = map(int, input().split())
a = [input() for _ in range(h)]
print(bfs(a))

Buggy python submission (verdict: Runtime Error):
from collections import deque


def bfs(S):  # 幅優先探索  # キュー
    dist = [-1] * (w * h)  # 前処理
    que = deque()
    for i, Si in enumerate(S):
        for j, Sij in enumerate(Si):
            if Sij == '#':
                dist[i + (w * j)] = 0
                que.append((i, j))

    while len(que) > 0:
        (x, y) = que.popleft()
        near = [(x + 1, y), (x - 1, y), (x, y + 1), (x, y - 1)]
        for i, j in near:  # 移動先の候補
            if 0 <= i < h and 0 <= j < w and dist[i][j] < 0:
                dist[i + (w * j)] = dist[x + (w * y)] + 1
                que.append((i, j))
    return dist[x][y]


h, w = map(int, input().split())
a = [input() for _ in range(h)]
print(bfs(a))


Fixed submission:
from collections import deque


def bfs(S):  # 幅優先探索  # キュー
    dist = [[-1] * w for _ in range(h)]  # 前処理
    que = deque()
    for i, Si in enumerate(S):
        for j, Sij in enumerate(Si):
            if Sij == '#':
                dist[i][j] = 0
                que.append((i, j))

    while len(que) > 0:
        (x, y) = que.popleft()
        near = [(x + 1, y), (x - 1, y), (x, y + 1), (x, y - 1)]
        for i, j in near:  # 移動先の候補
            if 0 <= i < h and 0 <= j < w and dist[i][j] < 0:
                dist[i][j] = dist[x][y] + 1
                que.append((i, j))
    return dist[x][y]


h, w = map(int, input().split())
a = [input() for _ in range(h)]
print(bfs(a))

Buggy python submission (verdict: Time Limit Exceeded):
from collections import deque


def bfs(S):  # 幅優先探索  # キュー
    que, frag = deque(), set()
    for i, Si in enumerate(S):
        for j, Sij in enumerate(Si):
            if Sij == '#':
                que.append((i, j, 0)), frag.add((i, j))

    while len(que) > 0:
        (x, y, d) = que.popleft()
        near = [(x + 1, y), (x - 1, y), (x, y + 1), (x, y - 1)]
        for i, j in near:  # 移動先の候補
            if (i, j) in frag:  # 処理済みか否か
                continue
            if 0 <= i < h and 0 <= j < w:
                que.append((i, j, d + 1)), frag.add((i, j))
    return d


h, w = map(int, input().split())
a = [input() for _ in range(h)]
print(bfs(a))


Fixed submission:
from collections import deque


def bfs(S):  # 幅優先探索  # キュー
    dist = [[-1] * w for _ in range(h)]  # 前処理
    que = deque()
    for i, Si in enumerate(S):
        for j, Sij in enumerate(Si):
            if Sij == '#':
                dist[i][j] = 0
                que.append((i, j))

    while len(que) > 0:
        (x, y) = que.popleft()
        near = [(x + 1, y), (x - 1, y), (x, y + 1), (x, y - 1)]
        for i, j in near:  # 移動先の候補
            if 0 <= i < h and 0 <= j < w and dist[i][j] < 0:
                dist[i][j] = dist[x][y] + 1
                que.append((i, j))
    return dist[x][y]


h, w = map(int, input().split())
a = [input() for _ in range(h)]
print(bfs(a))

Buggy python submission (verdict: Time Limit Exceeded):
from collections import deque


def bfs(S):  # 幅優先探索  # キュー
    dist = [-1] * (w * h)
    que, frag = deque(), set()
    for i, Si in enumerate(S):
        for j, Sij in enumerate(Si):
            if Sij == '#':
                dist[i * w + j] = 0
                que.append((i, j)), frag.add((i, j))

    while len(que) > 0:
        (x, y) = que.popleft()
        near = [(x + 1, y), (x - 1, y), (x, y + 1), (x, y - 1)]
        for i, j in near:  # 移動先の候補
            if (i, j) in frag:  # 処理済みか否か
                continue
            if 0 <= i < h and 0 <= j < w:
                dist[i * w + j] = dist[x * w + y] + 1
                que.append((i, j)), frag.add((i, j))
    return max(dist)


h, w = map(int, input().split())
a = [input() for _ in range(h)]
print(bfs(a))


Fixed submission:
from collections import deque


def bfs(S):  # 幅優先探索  # キュー
    dist = [[-1] * w for _ in range(h)]  # 前処理
    que = deque()
    for i, Si in enumerate(S):
        for j, Sij in enumerate(Si):
            if Sij == '#':
                dist[i][j] = 0
                que.append((i, j))

    while len(que) > 0:
        (x, y) = que.popleft()
        near = [(x + 1, y), (x - 1, y), (x, y + 1), (x, y - 1)]
        for i, j in near:  # 移動先の候補
            if 0 <= i < h and 0 <= j < w and dist[i][j] < 0:
                dist[i][j] = dist[x][y] + 1
                que.append((i, j))
    return dist[x][y]


h, w = map(int, input().split())
a = [input() for _ in range(h)]
print(bfs(a))

Buggy python submission (verdict: Time Limit Exceeded):
from collections import deque


def bfs(S):  # 幅優先探索  # キュー
    dist = [-1] * (w * h)
    que, frag = deque(), set()
    quead, fragad = que.append, frag.add
    for i, Si in enumerate(S):
        for j, Sij in enumerate(Si):
            if Sij == '#':
                dist[j + (w * i)] = 0
                quead((i, j)), fragad((i, j))

    while len(que) > 0:
        (x, y) = que.popleft()
        near = [(x + 1, y), (x - 1, y), (x, y + 1), (x, y - 1)]
        for i, j in near:  # 移動先の候補
            if (i, j) in frag:  # 処理済みか否か
                continue
            if 0 <= i < h and 0 <= j < w:
                dist[j + (w * i)] = dist[y + (w * x)] + 1
                quead((i, j)), fragad((i, j))
    return max(dist)


h, w = map(int, input().split())
a = [input() for _ in range(h)]
print(bfs(a))


Fixed submission:
from collections import deque


def bfs(S):  # 幅優先探索  # キュー
    dist = [[-1] * w for _ in range(h)]  # 前処理
    que = deque()
    for i, Si in enumerate(S):
        for j, Sij in enumerate(Si):
            if Sij == '#':
                dist[i][j] = 0
                que.append((i, j))

    while len(que) > 0:
        (x, y) = que.popleft()
        near = [(x + 1, y), (x - 1, y), (x, y + 1), (x, y - 1)]
        for i, j in near:  # 移動先の候補
            if 0 <= i < h and 0 <= j < w and dist[i][j] < 0:
                dist[i][j] = dist[x][y] + 1
                que.append((i, j))
    return dist[x][y]


h, w = map(int, input().split())
a = [input() for _ in range(h)]
print(bfs(a))

Buggy python submission (verdict: Time Limit Exceeded):
from collections import deque


def bfs(S):  # 幅優先探索  # キュー
    dist = [-1] * (w * h)
    que, frag = deque(), set()
    for i, Si in enumerate(S):
        for j, Sij in enumerate(Si):
            if Sij == '#':
                dist[j + (w * i)] = 0
                que.append((i, j)), frag.add((i, j))

    while len(que) > 0:
        (x, y) = que.popleft()
        near = [(x + 1, y), (x - 1, y), (x, y + 1), (x, y - 1)]
        for i, j in near:  # 移動先の候補
            if (i, j) in frag:  # 処理済みか否か
                continue
            if 0 <= i < h and 0 <= j < w:
                dist[j + (w * i)] = dist[y + (w * x)] + 1
                que.append((i, j)), frag.add((i, j))
    return max(dist)


h, w = map(int, input().split())
a = [input() for _ in range(h)]
print(bfs(a))


Fixed submission:
from collections import deque


def bfs(S):  # 幅優先探索  # キュー
    dist = [[-1] * w for _ in range(h)]  # 前処理
    que = deque()
    for i, Si in enumerate(S):
        for j, Sij in enumerate(Si):
            if Sij == '#':
                dist[i][j] = 0
                que.append((i, j))

    while len(que) > 0:
        (x, y) = que.popleft()
        near = [(x + 1, y), (x - 1, y), (x, y + 1), (x, y - 1)]
        for i, j in near:  # 移動先の候補
            if 0 <= i < h and 0 <= j < w and dist[i][j] < 0:
                dist[i][j] = dist[x][y] + 1
                que.append((i, j))
    return dist[x][y]


h, w = map(int, input().split())
a = [input() for _ in range(h)]
print(bfs(a))

Buggy python submission (verdict: Time Limit Exceeded):
from collections import deque


def bfs(S):  # 幅優先探索  # キュー
    dist = [-1] * (w * h)
    que, frag = deque(), set()
    for i, Si in enumerate(S):
        for j, Sij in enumerate(Si):
            if Sij == '#':
                dist[j + (w * i)] = 0
                que.append((i, j)), frag.add((i, j))
    
    while len(que) > 0:
        (x, y) = que.popleft()
        near = [(x + 1, y), (x - 1, y), (x, y + 1), (x, y - 1)]
        for i, j in near:  # 移動先の候補
            if (i, j) in frag:  # 処理済みか否か
                continue
            if 0 <= i < h and 0 <= j < w:
                dist[j + (w * i)] = dist[y + (w * x)] + 1
                que.append((i, j)), frag.add((i, j))
    return dist


h, w = map(int, input().split())
a = [input() for _ in range(h)]
print(max(bfs(a)))


Fixed submission:
from collections import deque


def bfs(S):  # 幅優先探索  # キュー
    dist = [[-1] * w for _ in range(h)]  # 前処理
    que = deque()
    for i, Si in enumerate(S):
        for j, Sij in enumerate(Si):
            if Sij == '#':
                dist[i][j] = 0
                que.append((i, j))

    while len(que) > 0:
        (x, y) = que.popleft()
        near = [(x + 1, y), (x - 1, y), (x, y + 1), (x, y - 1)]
        for i, j in near:  # 移動先の候補
            if 0 <= i < h and 0 <= j < w and dist[i][j] < 0:
                dist[i][j] = dist[x][y] + 1
                que.append((i, j))
    return dist[x][y]


h, w = map(int, input().split())
a = [input() for _ in range(h)]
print(bfs(a))

Buggy python submission (verdict: Runtime Error):
from collections import deque


def bfs(S):  # 幅優先探索  # キュー
    dist = [-1] * (w * h)
    que, frag = deque(), set()
    for i, Si in enumerate(S):
        for j, Sij in enumerate(Si):
            if Sij == '#':
                dist[i + (w * j)] = 0
                que.append((i, j)), frag.add((i, j))
    
    while len(que) > 0:
        (x, y) = que.popleft()
        near = [(x + 1, y), (x - 1, y), (x, y + 1), (x, y - 1)]
        for i, j in near:  # 移動先の候補
            if (i, j) in frag:  # 処理済みか否か
                continue
            if 0 <= i < h and 0 <= j < w:
                dist[i + (w * j)] = dist[x + (w * y)] + 1
                que.append((i, j)), frag.add((i, j))
    return dist


h, w = map(int, input().split())
a = [input() for _ in range(h)]
print(max(bfs(a)))


Fixed submission:
from collections import deque


def bfs(S):  # 幅優先探索  # キュー
    dist = [[-1] * w for _ in range(h)]  # 前処理
    que = deque()
    for i, Si in enumerate(S):
        for j, Sij in enumerate(Si):
            if Sij == '#':
                dist[i][j] = 0
                que.append((i, j))

    while len(que) > 0:
        (x, y) = que.popleft()
        near = [(x + 1, y), (x - 1, y), (x, y + 1), (x, y - 1)]
        for i, j in near:  # 移動先の候補
            if 0 <= i < h and 0 <= j < w and dist[i][j] < 0:
                dist[i][j] = dist[x][y] + 1
                que.append((i, j))
    return dist[x][y]


h, w = map(int, input().split())
a = [input() for _ in range(h)]
print(bfs(a))

Buggy python submission (verdict: Runtime Error):
from collections import deque


def bfs(S):  # 幅優先探索  # キュー
    dist = [-1] * (w + h)
    que, frag = deque(), set()
    for i, Si in enumerate(S):
        for j, Sij in enumerate(Si):
            if Sij == '#':
                dist[i + (h * j)] = 0
                que.append((i, j)), frag.add((i, j))

    while len(que) > 0:
        (x, y) = que.popleft()
        near = [(x + 1, y), (x - 1, y), (x, y + 1), (x, y - 1)]
        for i, j in near:  # 移動先の候補
            if (i, j) in frag:  # 処理済みか否か
                continue
            if 0 <= i < h and 0 <= j < w:
                dist[i + (h * j)] = dist[i + (h * j)] + 1
                que.append((i, j)), frag.add((i, j))
    return dist


h, w = map(int, input().split())
a = [input() for _ in range(h)]
ans = bfs(a)
print(max(max(ansi) for ansi in ans))


Fixed submission:
from collections import deque


def bfs(S):  # 幅優先探索  # キュー
    dist = [[-1] * w for _ in range(h)]  # 前処理
    que = deque()
    for i, Si in enumerate(S):
        for j, Sij in enumerate(Si):
            if Sij == '#':
                dist[i][j] = 0
                que.append((i, j))

    while len(que) > 0:
        (x, y) = que.popleft()
        near = [(x + 1, y), (x - 1, y), (x, y + 1), (x, y - 1)]
        for i, j in near:  # 移動先の候補
            if 0 <= i < h and 0 <= j < w and dist[i][j] < 0:
                dist[i][j] = dist[x][y] + 1
                que.append((i, j))
    return dist[x][y]


h, w = map(int, input().split())
a = [input() for _ in range(h)]
print(bfs(a))

Buggy python submission (verdict: Time Limit Exceeded):
import sys
input = sys.stdin.readline
from collections import deque


def bfs(S):  # 幅優先探索  # キュー
    dist = [[-1] * w for _ in range(h)]  # 前処理
    que, frag = deque(), set()
    for i, Si in enumerate(S):
        for j, Sij in enumerate(Si):
            if Sij == '#':
                dist[i][j] = 0
                que.append((i, j)), frag.add((i, j))

    while len(que) > 0:
        (x, y) = que.popleft()
        near = [(x + 1, y), (x - 1, y), (x, y + 1), (x, y - 1)]
        for i, j in near:  # 移動先の候補
            if (i, j) in frag:  # 処理済みか否か
                continue
            if 0 <= i < h and 0 <= j < w:
                dist[i][j] = dist[x][y] + 1
                que.append((i, j)), frag.add((i, j))
    return dist


h, w = map(int, input().split())
a = [input() for _ in range(h)]
ans = bfs(a)
print(max(max(ansi) for ansi in ans))


Fixed submission:
from collections import deque


def bfs(S):  # 幅優先探索  # キュー
    dist = [[-1] * w for _ in range(h)]  # 前処理
    que = deque()
    for i, Si in enumerate(S):
        for j, Sij in enumerate(Si):
            if Sij == '#':
                dist[i][j] = 0
                que.append((i, j))

    while len(que) > 0:
        (x, y) = que.popleft()
        near = [(x + 1, y), (x - 1, y), (x, y + 1), (x, y - 1)]
        for i, j in near:  # 移動先の候補
            if 0 <= i < h and 0 <= j < w and dist[i][j] < 0:
                dist[i][j] = dist[x][y] + 1
                que.append((i, j))
    return dist[x][y]


h, w = map(int, input().split())
a = [input() for _ in range(h)]
print(bfs(a))

Buggy python submission (verdict: Time Limit Exceeded):
import sys
input = sys.stdin.readline
from collections import deque


def bfs(S):  # 幅優先探索  # キュー
    dist = [[-1] * w for _ in range(h)]  # 前処理
    que, frag = deque(), set()
    for i, Si in enumerate(S):
        for j, Sij in enumerate(Si):
            if Sij == '#':
                dist[i][j] = 0
                que.append((i, j)), frag.add((i, j))

    while len(que) > 0:
        (x, y) = que.popleft()
        near = [(x + 1, y), (x - 1, y), (x, y + 1), (x, y - 1)]
        for i, j in near:  # 移動先の候補
            if (i, j) in frag:  # 処理済みか否か
                continue
            if 0 <= i < h and 0 <= j < w:
                dist[i][j] = dist[x][y] + 1
                que.append((i, j)), frag.add((i, j))
    return dist


if __name__ == '__main__':
    h, w = map(int, input().split())
    a = [input() for _ in range(h)]
    ans = bfs(a)
    print(max(max(ansi) for ansi in ans))


Fixed submission:
from collections import deque


def bfs(S):  # 幅優先探索  # キュー
    dist = [[-1] * w for _ in range(h)]  # 前処理
    que = deque()
    for i, Si in enumerate(S):
        for j, Sij in enumerate(Si):
            if Sij == '#':
                dist[i][j] = 0
                que.append((i, j))

    while len(que) > 0:
        (x, y) = que.popleft()
        near = [(x + 1, y), (x - 1, y), (x, y + 1), (x, y - 1)]
        for i, j in near:  # 移動先の候補
            if 0 <= i < h and 0 <= j < w and dist[i][j] < 0:
                dist[i][j] = dist[x][y] + 1
                que.append((i, j))
    return dist[x][y]


h, w = map(int, input().split())
a = [input() for _ in range(h)]
print(bfs(a))

Buggy python submission (verdict: Time Limit Exceeded):
from collections import deque


def bfs(S):  # 幅優先探索  # キュー
    dist = [[-1] * w for _ in range(h)]  # 前処理
    que, frag = deque(), set()
    for i, Si in enumerate(S):
        for j, Sij in enumerate(Si):
            if Sij == '#':
                dist[i][j] = 0
                que.append((i, j)), frag.add((i, j))

    while len(que) > 0:
        (x, y) = que.popleft()
        near = [(x + 1, y), (x - 1, y), (x, y + 1), (x, y - 1)]
        for i, j in near:  # 移動先の候補
            if (i, j) in frag:  # 処理済みか否か
                continue
            if 0 <= i < h and 0 <= j < w:
                dist[i][j] = dist[x][y] + 1
                que.append((i, j)), frag.add((i, j))
    return dist


if __name__ == '__main__':
    h, w = map(int, input().split())
    a = [input() for _ in range(h)]
    ans = bfs(a)
    print(max(max(ansi) for ansi in ans))


Fixed submission:
from collections import deque


def bfs(S):  # 幅優先探索  # キュー
    dist = [[-1] * w for _ in range(h)]  # 前処理
    que = deque()
    for i, Si in enumerate(S):
        for j, Sij in enumerate(Si):
            if Sij == '#':
                dist[i][j] = 0
                que.append((i, j))

    while len(que) > 0:
        (x, y) = que.popleft()
        near = [(x + 1, y), (x - 1, y), (x, y + 1), (x, y - 1)]
        for i, j in near:  # 移動先の候補
            if 0 <= i < h and 0 <= j < w and dist[i][j] < 0:
                dist[i][j] = dist[x][y] + 1
                que.append((i, j))
    return dist[x][y]


h, w = map(int, input().split())
a = [input() for _ in range(h)]
print(bfs(a))

Buggy python submission (verdict: Time Limit Exceeded):
from collections import deque


def bfs(S,H,W):  # 幅優先探索  # キュー
    dist = [[-1] * W for _ in range(H)]  # 前処理
    que, frag = deque(), set()
    for i, Si in enumerate(S):
        for j, Sij in enumerate(Si):
            if Sij == '#':
                dist[i][j] = 0
                que.append((i, j)), frag.add((i, j))

    while len(que) > 0:
        (x, y) = que.popleft()
        near = [(x + 1, y), (x - 1, y), (x, y + 1), (x, y - 1)]
        for i, j in near:  # 移動先の候補
            if (i, j) in frag:  # 処理済みか否か
                continue
            if 0 <= i < H and 0 <= j < W:
                dist[i][j] = dist[x][y] + 1
                que.append((i, j)), frag.add((i, j))
    return dist

def main():
    h, w = map(int, input().split())
    a = [input() for _ in range(h)]
    ans = bfs(a, h, w)
    print(max(max(ansi) for ansi in ans))

if __name__ == '__main__':
    main()


Fixed submission:
from collections import deque


def bfs(S):  # 幅優先探索  # キュー
    dist = [[-1] * w for _ in range(h)]  # 前処理
    que = deque()
    for i, Si in enumerate(S):
        for j, Sij in enumerate(Si):
            if Sij == '#':
                dist[i][j] = 0
                que.append((i, j))

    while len(que) > 0:
        (x, y) = que.popleft()
        near = [(x + 1, y), (x - 1, y), (x, y + 1), (x, y - 1)]
        for i, j in near:  # 移動先の候補
            if 0 <= i < h and 0 <= j < w and dist[i][j] < 0:
                dist[i][j] = dist[x][y] + 1
                que.append((i, j))
    return dist[x][y]


h, w = map(int, input().split())
a = [input() for _ in range(h)]
print(bfs(a))

Buggy python submission (verdict: Time Limit Exceeded):
from collections import deque


def bfs(S):  # 幅優先探索  # キュー
    dist = [[-1] * w for _ in range(h)]  # 前処理
    que, frag = deque(), set()
    for i, Si in enumerate(S):
        for j, Sij in enumerate(Si):
            if Sij == '#':
                dist[i][j] = 0
                que.append((i, j)), frag.add((i, j))

    while len(que) > 0:
        (x, y) = que.popleft()
        near = [(x + 1, y), (x - 1, y), (x, y + 1), (x, y - 1)]
        for i, j in near:  # 移動先の候補
            if (i, j) in frag:  # 処理済みか否か
                continue
            if 0 <= i < h and 0 <= j < w:
                dist[i][j] = dist[x][y] + 1
                que.append((i, j)), frag.add((i, j))
    return dist


h, w = map(int, input().split())
a = [input() for _ in range(h)]
ans = bfs(a)
print(max(max(ansi) for ansi in ans))


Fixed submission:
from collections import deque


def bfs(S):  # 幅優先探索  # キュー
    dist = [[-1] * w for _ in range(h)]  # 前処理
    que = deque()
    for i, Si in enumerate(S):
        for j, Sij in enumerate(Si):
            if Sij == '#':
                dist[i][j] = 0
                que.append((i, j))

    while len(que) > 0:
        (x, y) = que.popleft()
        near = [(x + 1, y), (x - 1, y), (x, y + 1), (x, y - 1)]
        for i, j in near:  # 移動先の候補
            if 0 <= i < h and 0 <= j < w and dist[i][j] < 0:
                dist[i][j] = dist[x][y] + 1
                que.append((i, j))
    return dist[x][y]


h, w = map(int, input().split())
a = [input() for _ in range(h)]
print(bfs(a))

Buggy python submission (verdict: Time Limit Exceeded):
from collections import deque


def bfs(S):  # 幅優先探索  # キュー
    dist = [[-1] * w for _ in range(h)]  # 前処理
    que, frag = deque(), set()
    for i, Si in enumerate(S):
        for j, Sij in enumerate(Si):
            if Sij == '#':
                dist[i][j] = 0
                que.append((i, j)), frag.add((i, j))

    while len(que) > 0:
        (x, y) = que.popleft()
        near = [(x + 1, y), (x - 1, y), (x, y + 1), (x, y - 1)]
        for i, j in near:  # 移動先の候補
            if ((i, j) in frag):  # 処理済みか否か
                continue
            if 0 <= i < h and 0 <= j < w:
                dist[i][j] = dist[x][y] + 1
                que.append((i, j)), frag.add((i, j))
    return dist


h, w = map(int, input().split())
a = [input() for _ in range(h)]
ans = bfs(a)
print(max(max(ansi) for ansi in ans))


Fixed submission:
from collections import deque


def bfs(S):  # 幅優先探索  # キュー
    dist = [[-1] * w for _ in range(h)]  # 前処理
    que = deque()
    for i, Si in enumerate(S):
        for j, Sij in enumerate(Si):
            if Sij == '#':
                dist[i][j] = 0
                que.append((i, j))

    while len(que) > 0:
        (x, y) = que.popleft()
        near = [(x + 1, y), (x - 1, y), (x, y + 1), (x, y - 1)]
        for i, j in near:  # 移動先の候補
            if 0 <= i < h and 0 <= j < w and dist[i][j] < 0:
                dist[i][j] = dist[x][y] + 1
                que.append((i, j))
    return dist[x][y]


h, w = map(int, input().split())
a = [input() for _ in range(h)]
print(bfs(a))

Buggy python submission (verdict: Time Limit Exceeded):
from collections import deque


def bfs(S):  # 幅優先探索  # キュー
    dist = [[-1] * w for _ in range(h)]  # 前処理
    que, frag = deque(), set()
    for i, Si in enumerate(S):
        for j, Sij in enumerate(Si):
            if Sij == '#':
                dist[i][j] = 0
                que.append((i, j)), frag.add((i, j))

    while len(que) > 0:
        (x, y) = que.popleft()
        near = [(x + 1, y), (x - 1, y), (x, y + 1), (x, y - 1)]
        for i, j in near:  # 移動先の候補
            if (i, j) in frag:  # 処理済みか否か
                continue
            if 0 <= i < h and 0 <= j < w:
                dist[i][j] = dist[x][y] + 1
                que.append((i, j)), frag.add((i, j))
    return dist


h, w = map(int, input().split())
a = [input() for _ in range(h)]
ans = bfs(a)
print(max(max(ansi) for ansi in ans))


Fixed submission:
from collections import deque


def bfs(S):  # 幅優先探索  # キュー
    dist = [[-1] * w for _ in range(h)]  # 前処理
    que = deque()
    for i, Si in enumerate(S):
        for j, Sij in enumerate(Si):
            if Sij == '#':
                dist[i][j] = 0
                que.append((i, j))

    while len(que) > 0:
        (x, y) = que.popleft()
        near = [(x + 1, y), (x - 1, y), (x, y + 1), (x, y - 1)]
        for i, j in near:  # 移動先の候補
            if 0 <= i < h and 0 <= j < w and dist[i][j] < 0:
                dist[i][j] = dist[x][y] + 1
                que.append((i, j))
    return dist[x][y]


h, w = map(int, input().split())
a = [input() for _ in range(h)]
print(bfs(a))

Buggy python submission (verdict: Runtime Error):
from collections import deque


def bfs(S):  # 幅優先探索  # キュー
    dist = [[-1] * w for _ in range(h)]  # 前処理
    que, frag = deque(), set()
    for i, Si in enumerate(S):
        for j, Sij in enumerate(Si):
            if Sij == '#':
                dist[i][j] = 0
                que.append((i, j)), frag.add((i, j))

    while len(que) > 0:
        (x, y) = que.popleft()
        near = [(x + 1, y), (x - 1, y), (x, y + 1), (x, y - 1)]
        for i, j in near:  # 移動先の候補
            if (i, j) in frag:  # 処理済みか否か
                continue
            if 0 <= i < h and 0 <= j < w:
                dist[i][j] = dist[x][y] + 1
                que.append((i, j)), frag.add((i, j))
    return dist


h, w = map(int, input().split())
a = [input() for _ in range(h)]
ans = bfs(a)
print(max(max(ansi) for ansi in ans)


Fixed submission:
from collections import deque


def bfs(S):  # 幅優先探索  # キュー
    dist = [[-1] * w for _ in range(h)]  # 前処理
    que = deque()
    for i, Si in enumerate(S):
        for j, Sij in enumerate(Si):
            if Sij == '#':
                dist[i][j] = 0
                que.append((i, j))

    while len(que) > 0:
        (x, y) = que.popleft()
        near = [(x + 1, y), (x - 1, y), (x, y + 1), (x, y - 1)]
        for i, j in near:  # 移動先の候補
            if 0 <= i < h and 0 <= j < w and dist[i][j] < 0:
                dist[i][j] = dist[x][y] + 1
                que.append((i, j))
    return dist[x][y]


h, w = map(int, input().split())
a = [input() for _ in range(h)]
print(bfs(a))

Buggy python submission (verdict: Time Limit Exceeded):
from collections import deque


def bfs(S):  # 幅優先探索  # キュー
    dist = [[-1] * w for _ in range(h)]  # 前処理
    que, frag = deque(), set()
    for i, Si in enumerate(S):
        for j, Sij in enumerate(Si):
            if Sij == '#':
                dist[i][j] = 0
                que.append((i, j)), frag.add((i, j))

    while len(que) > 0:
        (x, y) = que.popleft()
        near = [(x + 1, y), (x - 1, y), (x, y + 1), (x, y - 1)]
        for i, j in near:  # 移動先の候補
            if (i, j) in frag:  # 処理済みか否か
                continue
            if 0 <= i < h and 0 <= j < w:
                dist[i][j] = dist[x][y] + 1
                que.append((i, j)), frag.add((i, j))
    return dist


h, w = map(int, input().split())
a = [input() for _ in range(h)]
print(max(max(ans) for ans in bfs(a)))


Fixed submission:
from collections import deque


def bfs(S):  # 幅優先探索  # キュー
    dist = [[-1] * w for _ in range(h)]  # 前処理
    que = deque()
    for i, Si in enumerate(S):
        for j, Sij in enumerate(Si):
            if Sij == '#':
                dist[i][j] = 0
                que.append((i, j))

    while len(que) > 0:
        (x, y) = que.popleft()
        near = [(x + 1, y), (x - 1, y), (x, y + 1), (x, y - 1)]
        for i, j in near:  # 移動先の候補
            if 0 <= i < h and 0 <= j < w and dist[i][j] < 0:
                dist[i][j] = dist[x][y] + 1
                que.append((i, j))
    return dist[x][y]


h, w = map(int, input().split())
a = [input() for _ in range(h)]
print(bfs(a))