Buggy python submission (verdict: Time Limit Exceeded):
import sys, math, itertools, bisect, copy, re
from collections import Counter, deque, defaultdict

# from itertools import accumulate, permutations, combinations, takewhile, compress, cycle
# from functools import reduce
# from math import ceil, floor, log10, log2, factorial
# from pprint import pprint


INF = float('inf')
MOD = 10 ** 9 + 7
EPS = 10 ** -7
sys.setrecursionlimit(1000000)

# N = int(input())
# N,M = [int(x) for x in input().split()]
# V = [[0] * 100 for _ in range(100)]
# A = [int(input()) for _ in range(N)]
# DP = [[0] * 100 for _ in range(100)]
# DP = defaultdict(lambda: float('inf'))

H, W = [int(x) for x in input().split()]
A = []
BQ = deque()
for _ in range(H):
    L = list(input())
    A.append(L)

bCnt = 0
for x in range(W):
    for y in range(H):
        if A[y][x] == '#':
            BQ.append((x, y))
            bCnt += 1


def check(a):
    a2 = sum(a, [])
    cnt = a2.count('.')
    return cnt == 0


def ok(x, y, W, H):
    if x >= 0 and x < W and y >= 0 and y < H:
        return True
    return False


# X,Y座標
DX = [1, -1, 0, 0]
DY = [0, 0, 1, -1]

cnt = 0

while bCnt != H * W:
    newBQ = deque()
    for (x, y) in BQ:
        for (dx, dy) in zip(DX, DY):
            X = x + dx
            Y = y + dy
            if ok(X, Y, W, H) and A[Y][X] == '.':
                A[Y][X] = '#'
                newBQ.append((X, Y))
                bCnt += 1

    cnt += 1

    # print("len:{}".format(len(newBQ)))
    # for a in A:
    #     print(a)
    # print("---")

    BQ = newBQ

print(cnt)


Fixed submission:
import sys, math, itertools, bisect, copy, re
from collections import Counter, deque, defaultdict

# from itertools import accumulate, permutations, combinations, takewhile, compress, cycle
# from functools import reduce
# from math import ceil, floor, log10, log2, factorial
# from pprint import pprint


INF = float('inf')
MOD = 10 ** 9 + 7
EPS = 10 ** -7
sys.setrecursionlimit(1000000)

# N = int(input())
# N,M = [int(x) for x in input().split()]
# V = [[0] * 100 for _ in range(100)]
# A = [int(input()) for _ in range(N)]
# DP = [[0] * 100 for _ in range(100)]
# DP = defaultdict(lambda: float('inf'))

H, W = [int(x) for x in input().split()]
A = []
BQ = deque()
for _ in range(H):
    L = list(input())
    A.append(L)

bCnt = 0
for x in range(W):
    for y in range(H):
        if A[y][x] == '#':
            BQ.append((x, y))
            bCnt += 1


def check(a):
    a2 = sum(a, [])
    cnt = a2.count('.')
    return cnt == 0


def ok(x, y, W, H):
    if x >= 0 and x < W and y >= 0 and y < H:
        return True
    return False


# X,Y座標
DX = [1, -1, 0, 0]
DY = [0, 0, 1, -1]

cnt = 0

while bCnt != H * W:
    newBQ = deque()
    for (x, y) in BQ:
        for (dx, dy) in zip(DX, DY):
            X = x + dx
            Y = y + dy
            if ok(X, Y, W, H) and A[Y][X] == '.':
                A[Y][X] = '#'
                newBQ.append((X, Y))
                bCnt += 1

    cnt += 1

    # print("len:{}".format(len(newBQ)))
    # for a in A:
    #     print(a)
    # print("---")

    BQ = newBQ

print(cnt)

Buggy python submission (verdict: Time Limit Exceeded):
import sys, math, itertools, bisect, copy, re
from collections import Counter, deque, defaultdict

# from itertools import accumulate, permutations, combinations, takewhile, compress, cycle
# from functools import reduce
# from math import ceil, floor, log10, log2, factorial
# from pprint import pprint


INF = float('inf')
MOD = 10 ** 9 + 7
EPS = 10 ** -7
sys.setrecursionlimit(1000000)

# N = int(input())
# N,M = [int(x) for x in input().split()]
# V = [[0] * 100 for _ in range(100)]
# A = [int(input()) for _ in range(N)]
# DP = [[0] * 100 for _ in range(100)]
# DP = defaultdict(lambda: float('inf'))

H, W = [int(x) for x in input().split()]
A = []
BQ = deque()
for _ in range(H):
    L = list(input())
    A.append(L)

for x in range(W):
    for y in range(H):
        if A[y][x] == '#':
            BQ.append((x, y))


def check(a):
    a2 = sum(a, [])
    cnt = a2.count('.')
    return cnt == 0


def ok(x, y, W, H):
    if x >= 0 and x < W and y >= 0 and y < H:
        return True
    return False


# X,Y座標
DX = [1, -1, 0, 0]
DY = [0, 0, 1, -1]

cnt = 0
while check(A) == False:
    newBQ = deque()
    for (x, y) in BQ:
        for (dx, dy) in zip(DX, DY):
            X = x + dx
            Y = y + dy
            if ok(X, Y, W, H) and A[Y][X] == '.':
                A[Y][X] = '#'
                newBQ.append((X, Y))
    cnt += 1

    # print("len:{}".format(len(newBQ)))
    # for a in A:
    #     print(a)
    # print("---")

    BQ = newBQ

print(cnt)


Fixed submission:
import sys, math, itertools, bisect, copy, re
from collections import Counter, deque, defaultdict

# from itertools import accumulate, permutations, combinations, takewhile, compress, cycle
# from functools import reduce
# from math import ceil, floor, log10, log2, factorial
# from pprint import pprint


INF = float('inf')
MOD = 10 ** 9 + 7
EPS = 10 ** -7
sys.setrecursionlimit(1000000)

# N = int(input())
# N,M = [int(x) for x in input().split()]
# V = [[0] * 100 for _ in range(100)]
# A = [int(input()) for _ in range(N)]
# DP = [[0] * 100 for _ in range(100)]
# DP = defaultdict(lambda: float('inf'))

H, W = [int(x) for x in input().split()]
A = []
BQ = deque()
for _ in range(H):
    L = list(input())
    A.append(L)

bCnt = 0
for x in range(W):
    for y in range(H):
        if A[y][x] == '#':
            BQ.append((x, y))
            bCnt += 1


def check(a):
    a2 = sum(a, [])
    cnt = a2.count('.')
    return cnt == 0


def ok(x, y, W, H):
    if x >= 0 and x < W and y >= 0 and y < H:
        return True
    return False


# X,Y座標
DX = [1, -1, 0, 0]
DY = [0, 0, 1, -1]

cnt = 0

while bCnt != H * W:
    newBQ = deque()
    for (x, y) in BQ:
        for (dx, dy) in zip(DX, DY):
            X = x + dx
            Y = y + dy
            if ok(X, Y, W, H) and A[Y][X] == '.':
                A[Y][X] = '#'
                newBQ.append((X, Y))
                bCnt += 1

    cnt += 1

    # print("len:{}".format(len(newBQ)))
    # for a in A:
    #     print(a)
    # print("---")

    BQ = newBQ

print(cnt)

Buggy python submission (verdict: Runtime Error):
import sys, math, itertools, bisect, copy, re
from collections import Counter, deque, defaultdict

# from itertools import accumulate, permutations, combinations, takewhile, compress, cycle
# from functools import reduce
# from math import ceil, floor, log10, log2, factorial
# from pprint import pprint


INF = float('inf')
MOD = 10 ** 9 + 7
EPS = 10 ** -7
sys.setrecursionlimit(1000000)

# N = int(input())
# N,M = [int(x) for x in input().split()]
# V = [[0] * 100 for _ in range(100)]
# A = [int(input()) for _ in range(N)]
# DP = [[0] * 100 for _ in range(100)]
# DP = defaultdict(lambda: float('inf'))

H, W = [int(x) for x in input().split()]
A = []
BQ = deque()
for _ in range(H):
    L = list(input())
    A.append(L)

for x in range(W):
    for y in range(H):
        if A[x][y] == '#':
            BQ.append((x, y))


def check(a):
    a2 = sum(a, [])
    cnt = a2.count('.')
    return cnt == 0


def ok(x, y, W, H):
    if x >= 0 and x < W and y >= 0 and y < H:
        return True
    return False


# X,Y座標
DX = [1, -1, 0, 0, 0]
DY = [0, 0, 1, -1, 0]

cnt = 0
while check(A) == False:
    newBQ = deque()
    for (x, y) in BQ:
        for (dx, dy) in zip(DX, DY):
            X = x + dx
            Y = y + dy
            if ok(X, Y, W, H) and A[X][Y] == '.':
                A[X][Y] = '#'
                newBQ.append((X, Y))
    cnt += 1
    BQ = newBQ

    # for a in A:
    #     print(a)
    # print("---")

print(cnt)


Fixed submission:
import sys, math, itertools, bisect, copy, re
from collections import Counter, deque, defaultdict

# from itertools import accumulate, permutations, combinations, takewhile, compress, cycle
# from functools import reduce
# from math import ceil, floor, log10, log2, factorial
# from pprint import pprint


INF = float('inf')
MOD = 10 ** 9 + 7
EPS = 10 ** -7
sys.setrecursionlimit(1000000)

# N = int(input())
# N,M = [int(x) for x in input().split()]
# V = [[0] * 100 for _ in range(100)]
# A = [int(input()) for _ in range(N)]
# DP = [[0] * 100 for _ in range(100)]
# DP = defaultdict(lambda: float('inf'))

H, W = [int(x) for x in input().split()]
A = []
BQ = deque()
for _ in range(H):
    L = list(input())
    A.append(L)

bCnt = 0
for x in range(W):
    for y in range(H):
        if A[y][x] == '#':
            BQ.append((x, y))
            bCnt += 1


def check(a):
    a2 = sum(a, [])
    cnt = a2.count('.')
    return cnt == 0


def ok(x, y, W, H):
    if x >= 0 and x < W and y >= 0 and y < H:
        return True
    return False


# X,Y座標
DX = [1, -1, 0, 0]
DY = [0, 0, 1, -1]

cnt = 0

while bCnt != H * W:
    newBQ = deque()
    for (x, y) in BQ:
        for (dx, dy) in zip(DX, DY):
            X = x + dx
            Y = y + dy
            if ok(X, Y, W, H) and A[Y][X] == '.':
                A[Y][X] = '#'
                newBQ.append((X, Y))
                bCnt += 1

    cnt += 1

    # print("len:{}".format(len(newBQ)))
    # for a in A:
    #     print(a)
    # print("---")

    BQ = newBQ

print(cnt)

Buggy python submission (verdict: Time Limit Exceeded):
import sys, math, itertools, bisect, copy, re
from collections import Counter, deque, defaultdict

# from itertools import accumulate, permutations, combinations, takewhile, compress, cycle
# from functools import reduce
# from math import ceil, floor, log10, log2, factorial
# from pprint import pprint


INF = float('inf')
MOD = 10 ** 9 + 7
EPS = 10 ** -7
sys.setrecursionlimit(1000000)

# N = int(input())
# N,M = [int(x) for x in input().split()]
# V = [[0] * 100 for _ in range(100)]
# A = [int(input()) for _ in range(N)]
# DP = [[0] * 100 for _ in range(100)]
# DP = defaultdict(lambda: float('inf'))

H, W = [int(x) for x in input().split()]
L = []
for _ in range(H):
    L.append(list(input()))

dx = [1, -1, 0, 0, 0]
dy = [0, 0, 1, -1, 0]


def check(M):
    return all([x == '#' for x in sum(M, [])])


def ok(x, y, W, H):
    if x >= 0 and x < W and y >= 0 and y < H:
        return True
    return False


def f(m1):
    ret = [['.'] * W for _ in range(H)]
    for x in range(W):
        for y in range(H):
            for i in range(5):
                X = x + dx[i]
                Y = y + dy[i]
                if ok(X, Y, W, H):
                    if m1[X][Y] == '#':
                        ret[x][y] = '#'
    return ret


def p(M):
    for l in M:
        print(l)


m1 = copy.deepcopy(L)
cnt = 0
while check(m1) == False:
    tmp = copy.deepcopy(m1)
    m1 = f(tmp)
    cnt += 1

print(cnt)


Fixed submission:
import sys, math, itertools, bisect, copy, re
from collections import Counter, deque, defaultdict

# from itertools import accumulate, permutations, combinations, takewhile, compress, cycle
# from functools import reduce
# from math import ceil, floor, log10, log2, factorial
# from pprint import pprint


INF = float('inf')
MOD = 10 ** 9 + 7
EPS = 10 ** -7
sys.setrecursionlimit(1000000)

# N = int(input())
# N,M = [int(x) for x in input().split()]
# V = [[0] * 100 for _ in range(100)]
# A = [int(input()) for _ in range(N)]
# DP = [[0] * 100 for _ in range(100)]
# DP = defaultdict(lambda: float('inf'))

H, W = [int(x) for x in input().split()]
A = []
BQ = deque()
for _ in range(H):
    L = list(input())
    A.append(L)

bCnt = 0
for x in range(W):
    for y in range(H):
        if A[y][x] == '#':
            BQ.append((x, y))
            bCnt += 1


def check(a):
    a2 = sum(a, [])
    cnt = a2.count('.')
    return cnt == 0


def ok(x, y, W, H):
    if x >= 0 and x < W and y >= 0 and y < H:
        return True
    return False


# X,Y座標
DX = [1, -1, 0, 0]
DY = [0, 0, 1, -1]

cnt = 0

while bCnt != H * W:
    newBQ = deque()
    for (x, y) in BQ:
        for (dx, dy) in zip(DX, DY):
            X = x + dx
            Y = y + dy
            if ok(X, Y, W, H) and A[Y][X] == '.':
                A[Y][X] = '#'
                newBQ.append((X, Y))
                bCnt += 1

    cnt += 1

    # print("len:{}".format(len(newBQ)))
    # for a in A:
    #     print(a)
    # print("---")

    BQ = newBQ

print(cnt)

Buggy python submission (verdict: Time Limit Exceeded):
import sys, math, itertools, bisect, copy, re
from collections import Counter, deque, defaultdict

# from itertools import accumulate, permutations, combinations, takewhile, compress, cycle
# from functools import reduce
# from math import ceil, floor, log10, log2, factorial
# from pprint import pprint


INF = float('inf')
MOD = 10 ** 9 + 7
EPS = 10 ** -7
sys.setrecursionlimit(1000000)

# N = int(input())
# N,M = [int(x) for x in input().split()]
# V = [[0] * 100 for _ in range(100)]
# A = [int(input()) for _ in range(N)]
# DP = [[0] * 100 for _ in range(100)]
# DP = defaultdict(lambda: float('inf'))

H, W = [int(x) for x in input().split()]
L = []
for _ in range(H):
    L.append(list(input()))

dx = [1, -1, 0, 0, 0]
dy = [0, 0, 1, -1, 0]


def check(M):
    return all([x == '#' for x in sum(M, [])])


def ok(x, y, W, H):
    if x >= 0 and x < W and y >= 0 and y < H:
        return True
    return False


def f(m1):
    ret = [['.'] * W for _ in range(H)]
    for x in range(W):
        for y in range(H):
            for i in range(5):
                X = x + dx[i]
                Y = y + dy[i]
                if ok(X, Y, W, H):
                    if m1[X][Y] == '#':
                        ret[x][y] = '#'
    return ret


def p(M):
    for l in M:
        print(l)


m1 = copy.deepcopy(L)
cnt = 0
while check(m1) == False:
    tmp = copy.deepcopy(m1)
    m1 = f(tmp)
    cnt += 1

print(cnt)


Fixed submission:
import sys, math, itertools, bisect, copy, re
from collections import Counter, deque, defaultdict

# from itertools import accumulate, permutations, combinations, takewhile, compress, cycle
# from functools import reduce
# from math import ceil, floor, log10, log2, factorial
# from pprint import pprint


INF = float('inf')
MOD = 10 ** 9 + 7
EPS = 10 ** -7
sys.setrecursionlimit(1000000)

# N = int(input())
# N,M = [int(x) for x in input().split()]
# V = [[0] * 100 for _ in range(100)]
# A = [int(input()) for _ in range(N)]
# DP = [[0] * 100 for _ in range(100)]
# DP = defaultdict(lambda: float('inf'))

H, W = [int(x) for x in input().split()]
A = []
BQ = deque()
for _ in range(H):
    L = list(input())
    A.append(L)

bCnt = 0
for x in range(W):
    for y in range(H):
        if A[y][x] == '#':
            BQ.append((x, y))
            bCnt += 1


def check(a):
    a2 = sum(a, [])
    cnt = a2.count('.')
    return cnt == 0


def ok(x, y, W, H):
    if x >= 0 and x < W and y >= 0 and y < H:
        return True
    return False


# X,Y座標
DX = [1, -1, 0, 0]
DY = [0, 0, 1, -1]

cnt = 0

while bCnt != H * W:
    newBQ = deque()
    for (x, y) in BQ:
        for (dx, dy) in zip(DX, DY):
            X = x + dx
            Y = y + dy
            if ok(X, Y, W, H) and A[Y][X] == '.':
                A[Y][X] = '#'
                newBQ.append((X, Y))
                bCnt += 1

    cnt += 1

    # print("len:{}".format(len(newBQ)))
    # for a in A:
    #     print(a)
    # print("---")

    BQ = newBQ

print(cnt)