Buggy python submission (verdict: Time Limit Exceeded):
H,W = list(map(int,input().split()))
Ch,Cw = list(map(int,input().split()))
Dh,Dw = list(map(int,input().split()))
Ch,Cw,Dh,Dw = Ch-1,Cw-1,Dh-1,Dw-1

from collections import deque
maze = []
for i in range(H):
    maze.append(list(input()))
times = [[-1]*W for i in range(H)]

dh = [1, 0, -1, 0]
dw = [0, 1, 0, -1]
que = deque([])
que.append((Ch, Cw))
times[Ch][Cw] = 0
cnt = 0
flag = 0
while flag==0:
    loc = deque([])
    while que:
        p = que.popleft()
        wallflag = 0
        if p[0] == Dh and p[1] == Dw:
            times[Dh][Dw] = cnt
            flag = 1
            break
        for i in range(4):
            nh = p[0] + dh[i]
            nw = p[1] + dw[i]
            if (0<=nh<H)and(0<=nw<W)and(maze[nh][nw]!="#")and(times[nh][nw]==-1):
                que.append((nh, nw))
                times[nh][nw] = cnt
            if (0<=nh<H)and(0<=nw<W)and(maze[nh][nw]=="#"):
                wallflag = 1
        if wallflag ==1:
            loc.append(p)
    que = deque([])
    while loc:
        p = loc.popleft()
        for i in range(-2,3):
            for j in range(-2,3):
                nh = p[0] + i
                nw = p[1] + j
                if (0<=nh<H)and(0<=nw<W)and(maze[nh][nw]!="#")and(times[nh][nw]==-1):
                    que.append((nh, nw))
    if len(que)==0:
        break
    cnt += 1

if times[Dh][Dw] == -1:
    print(-1)
else:
    print(times[Dh][Dw])

Fixed submission:
from collections import deque
H, W = map(int, input().split())
si, sj = map(int, input().split())
gi, gj = map(int, input().split())
si, sj, gi, gj = si-1+2, sj-1+2, gi-1+2, gj-1+2
X = [[1] * (W + 4)] * 2 + [[1] * 2 + [1 if a == "#" else 0for a in input()] + [1] * 2 for _ in range(H)] + [[1] * (W + 4)] * 2
H += 4
W += 4

Y = [(-1, 0), (0, -1), (0, 0), (0, 1), (1, 0)]
Z = [(-2, -2), (-2, -1), (-2, 0), (-2, 1), (-2, 2), (-1, -2), (-1, -1), (-1, 1), (-1, 2), (0, -2), (0, 2), (1, -2), (1, -1), (1, 1), (1, 2), (2, -2), (2, -1), (2, 0), (2, 1), (2, 2)]

def BFS():
    Q = deque([(si, sj)])
    D = [-1] * (H * W)
    D[si*W + sj] = 0
    while Q:
        i, j = Q.popleft()
        x = i * W + j
        for di, dj in Y:
            ni, nj = i+di, j+dj
            y = ni * W + nj
            if X[ni][nj] == 0:
                if D[y] == -1 or D[y] > D[x]:
                    D[y] = D[x]
                    Q.appendleft((ni, nj))
        for di, dj in Z:
            ni, nj = i+di, j+dj
            y = ni * W + nj
            if X[ni][nj] == 0:
                if D[y] == -1:
                    D[y] = D[x] + 1
                    Q.append((ni, nj))
    return D[gi * W + gj]

print(BFS())

Buggy python submission (verdict: Time Limit Exceeded):
H,W = list(map(int,input().split()))
Ch,Cw = list(map(int,input().split()))
Dh,Dw = list(map(int,input().split()))
Ch,Cw,Dh,Dw = Ch-1,Cw-1,Dh-1,Dw-1

from collections import deque
maze = []
for i in range(H):
    maze.append(list(input()))
times = [[10000000]*W for i in range(H)]

dh = [1, 0, -1, 0]
dw = [0, 1, 0, -1]
que = deque([])
que.append((Ch, Cw))
times[Ch][Cw] = 0
cnt = 0
flag = 0
while flag==0:
    loc = deque([])
    while que:
        p = que.popleft()
        wallflag = 0
        if p[0] == Dh and p[1] == Dw:
            times[Dh][Dw] = cnt
            flag = 1
            break
        for i in range(4):
            nh = p[0] + dh[i]
            nw = p[1] + dw[i]
            if (0<=nh<H)and(0<=nw<W)and(maze[nh][nw]!="#")and(times[nh][nw]==10000000):
                que.append((nh, nw))
                times[nh][nw] = cnt
            if (0<=nh<H)and(0<=nw<W)and(maze[nh][nw]=="#"):
                wallflag = 1
        if wallflag ==1:
            loc.append(p)
    que = deque([])
    while loc:
        p = loc.popleft()
        for i in range(-2,3):
            for j in range(-2,3):
                nh = p[0] + i
                nw = p[1] + j
                if (0<=nh<H)and(0<=nw<W)and(maze[nh][nw]!="#")and(times[nh][nw]==10000000):
                    que.append((nh, nw))
    if len(que)==0:
        break
    cnt += 1

if times[Dh][Dw] == 10000000:
    print(-1)
else:
    print(times[Dh][Dw])

Fixed submission:
from collections import deque
H, W = map(int, input().split())
si, sj = map(int, input().split())
gi, gj = map(int, input().split())
si, sj, gi, gj = si-1+2, sj-1+2, gi-1+2, gj-1+2
X = [[1] * (W + 4)] * 2 + [[1] * 2 + [1 if a == "#" else 0for a in input()] + [1] * 2 for _ in range(H)] + [[1] * (W + 4)] * 2
H += 4
W += 4

Y = [(-1, 0), (0, -1), (0, 0), (0, 1), (1, 0)]
Z = [(-2, -2), (-2, -1), (-2, 0), (-2, 1), (-2, 2), (-1, -2), (-1, -1), (-1, 1), (-1, 2), (0, -2), (0, 2), (1, -2), (1, -1), (1, 1), (1, 2), (2, -2), (2, -1), (2, 0), (2, 1), (2, 2)]

def BFS():
    Q = deque([(si, sj)])
    D = [-1] * (H * W)
    D[si*W + sj] = 0
    while Q:
        i, j = Q.popleft()
        x = i * W + j
        for di, dj in Y:
            ni, nj = i+di, j+dj
            y = ni * W + nj
            if X[ni][nj] == 0:
                if D[y] == -1 or D[y] > D[x]:
                    D[y] = D[x]
                    Q.appendleft((ni, nj))
        for di, dj in Z:
            ni, nj = i+di, j+dj
            y = ni * W + nj
            if X[ni][nj] == 0:
                if D[y] == -1:
                    D[y] = D[x] + 1
                    Q.append((ni, nj))
    return D[gi * W + gj]

print(BFS())

Buggy python submission (verdict: Time Limit Exceeded):
H,W = list(map(int,input().split()))
Ch,Cw = list(map(int,input().split()))
Dh,Dw = list(map(int,input().split()))
Ch,Cw,Dh,Dw = Ch-1,Cw-1,Dh-1,Dw-1

from collections import deque
maze = []
for i in range(H):
    maze.append(list(input()))
times = [[10000000]*W for i in range(H)]

dh = [1, 0, -1, 0]
dw = [0, 1, 0, -1]
que = deque([])
que.append((Ch, Cw))
times[Ch][Cw] = 0
cnt = 0
flag = 0
while flag==0:
    loc = deque([])
    while que:
        p = que.popleft()
        wallflag = 0
        if p[0] == Dh and p[1] == Dw:
            times[Dh][Dw] = cnt
            flag = 1
            break
        for i in range(4):
            nh = p[0] + dh[i]
            nw = p[1] + dw[i]
            if (0<=nh<H)and(0<=nw<W)and(maze[nh][nw]!="#")and(times[nh][nw]==10000000):
                que.append((nh, nw))
                times[nh][nw] = cnt
            if (0<=nh<H)and(0<=nw<W)and(maze[nh][nw]=="#"):
                wallflag = 1
        if wallflag ==1:
            loc.append(p)
    que = deque([])
    while loc:
        p = loc.popleft()
        for i in range(-2,3):
            for j in range(-2,3):
                nh = p[0] + i
                nw = p[1] + j
                if (0<=nh<H)and(0<=nw<W)and(maze[nh][nw]!="#")and(times[nh][nw]==10000000):
                    que.append((nh, nw))
    if len(que)==0:
        break
    cnt += 1

if times[Dh][Dw] == 10000000:
    print(-1)
else:
    print(times[Dh][Dw])

Fixed submission:
from collections import deque
H, W = map(int, input().split())
si, sj = map(int, input().split())
gi, gj = map(int, input().split())
si, sj, gi, gj = si-1+2, sj-1+2, gi-1+2, gj-1+2
X = [[1] * (W + 4)] * 2 + [[1] * 2 + [1 if a == "#" else 0for a in input()] + [1] * 2 for _ in range(H)] + [[1] * (W + 4)] * 2
H += 4
W += 4

Y = [(-1, 0), (0, -1), (0, 0), (0, 1), (1, 0)]
Z = [(-2, -2), (-2, -1), (-2, 0), (-2, 1), (-2, 2), (-1, -2), (-1, -1), (-1, 1), (-1, 2), (0, -2), (0, 2), (1, -2), (1, -1), (1, 1), (1, 2), (2, -2), (2, -1), (2, 0), (2, 1), (2, 2)]

def BFS():
    Q = deque([(si, sj)])
    D = [-1] * (H * W)
    D[si*W + sj] = 0
    while Q:
        i, j = Q.popleft()
        x = i * W + j
        for di, dj in Y:
            ni, nj = i+di, j+dj
            y = ni * W + nj
            if X[ni][nj] == 0:
                if D[y] == -1 or D[y] > D[x]:
                    D[y] = D[x]
                    Q.appendleft((ni, nj))
        for di, dj in Z:
            ni, nj = i+di, j+dj
            y = ni * W + nj
            if X[ni][nj] == 0:
                if D[y] == -1:
                    D[y] = D[x] + 1
                    Q.append((ni, nj))
    return D[gi * W + gj]

print(BFS())

Buggy python submission (verdict: Time Limit Exceeded):
H,W = list(map(int,input().split()))
Ch,Cw = list(map(int,input().split()))
Dh,Dw = list(map(int,input().split()))
Ch,Cw,Dh,Dw = Ch-1,Cw-1,Dh-1,Dw-1

from collections import deque
maze = []
for i in range(H):
    maze.append(list(input()))
times = [[10000000]*W for i in range(H)]

dh = [1, 0, -1, 0]
dw = [0, 1, 0, -1]
que = deque([])
que.append((Ch, Cw))
times[Ch][Cw] = 0
cnt = 0
flag = 0
while flag==0:
    loc = deque([])
    while que:
        p = que.popleft()
        loc.append(p)
        if p[0] == Dh and p[1] == Dw:
            times[Dh][Dw] = cnt
            flag = 1
            break
        for i in range(4):
            nh = p[0] + dh[i]
            nw = p[1] + dw[i]
            if (0<=nh<H)and(0<=nw<W)and(maze[nh][nw]!="#")and(times[nh][nw]==10000000):
                que.append((nh, nw))
                times[nh][nw] = cnt
    que = deque([])
    while loc:
        p = loc.popleft()
        for i in range(-2,3):
            for j in range(-2,3):
                nh = p[0] + i
                nw = p[1] + j
                if (0<=nh<H)and(0<=nw<W)and(maze[nh][nw]!="#")and(times[nh][nw]==10000000):
                    que.append((nh, nw))
    if len(que)==0:
        break
    cnt += 1

if times[Dh][Dw] == 10000000:
    print(-1)
else:
    print(times[Dh][Dw])

Fixed submission:
from collections import deque
H, W = map(int, input().split())
si, sj = map(int, input().split())
gi, gj = map(int, input().split())
si, sj, gi, gj = si-1+2, sj-1+2, gi-1+2, gj-1+2
X = [[1] * (W + 4)] * 2 + [[1] * 2 + [1 if a == "#" else 0for a in input()] + [1] * 2 for _ in range(H)] + [[1] * (W + 4)] * 2
H += 4
W += 4

Y = [(-1, 0), (0, -1), (0, 0), (0, 1), (1, 0)]
Z = [(-2, -2), (-2, -1), (-2, 0), (-2, 1), (-2, 2), (-1, -2), (-1, -1), (-1, 1), (-1, 2), (0, -2), (0, 2), (1, -2), (1, -1), (1, 1), (1, 2), (2, -2), (2, -1), (2, 0), (2, 1), (2, 2)]

def BFS():
    Q = deque([(si, sj)])
    D = [-1] * (H * W)
    D[si*W + sj] = 0
    while Q:
        i, j = Q.popleft()
        x = i * W + j
        for di, dj in Y:
            ni, nj = i+di, j+dj
            y = ni * W + nj
            if X[ni][nj] == 0:
                if D[y] == -1 or D[y] > D[x]:
                    D[y] = D[x]
                    Q.appendleft((ni, nj))
        for di, dj in Z:
            ni, nj = i+di, j+dj
            y = ni * W + nj
            if X[ni][nj] == 0:
                if D[y] == -1:
                    D[y] = D[x] + 1
                    Q.append((ni, nj))
    return D[gi * W + gj]

print(BFS())