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

H, W=map(int, input().split())
ch, cw=map(int, input().split())
dh, dw=map(int, input().split())
ch-=1
cw-=1
dh-=1
dw-=1

grid=["0"]*H
for i in range(H):
    s=input()
    grid[i]=s

Inf=10**12
cost=[[Inf] * W for i in range(H)]

walk=[(0, 1), (0, -1), (-1, 0), (1, 0)]
warp=[]
for i in range(-2, 3):
    for j in range(-2, 3):
        if i==0 and j==0:
            continue
        if (i, j) not in walk:
            warp.append((i, j))

q=deque()
cost[ch][cw]=0
q.append((ch, cw, 0))

while q:
    x, y, c=q.popleft()
    for dx, dy in walk:
        nx = x+dx
        ny = y+dy
        if 0<= nx < H and 0<= ny < W and grid[nx][ny]=="." and cost[nx][ny]>c:
            cost[nx][ny]=c
            q.appendleft((nx, ny, c))
    
    for dx, dy in warp:
        nx = x+dx
        ny = y+dy
        if 0<= nx < H and 0<= ny < W and grid[nx][ny]=="." and cost[nx][ny]>c+1:
            cost[nx][ny]=c+1
            q.append((nx, ny, c+1))


if cost[dh][dw]==Inf:
    print(-1)
else:
    ans=cost[dh][dw]
    print(ans)

Fixed submission:
from collections import deque


H, W = map(int, input().split())
Ch, Cw = map(lambda x: int(x) - 1, input().split())
Dh, Dw = map(lambda x: int(x) - 1, input().split())
maze = [input() for _ in range(H)]

INF = 10 ** 12
path = [[INF] * W for _ in range(H)]  # path: 各マスへの移動コスト

# walk:移動A, warp:移動B
walk = [(0, 1), (0, -1), (-1, 0), (1, 0)]
warp = [(i, j) for i in range(-2, 3) for j in range(-2, 3) if (i, j) not in [(0, 0)] + walk]

q = deque()
path[Ch][Cw] = 0
q.append((Ch, Cw, 0))

while q:
    x, y, s = q.popleft()
    for dx, dy in walk:  # 移動A
        nx = x + dx
        ny = y + dy
        if 0 <= nx < H and 0 <= ny < W and maze[nx][ny] == '.' and path[nx][ny] > s:
            path[nx][ny] = s
            q.appendleft((nx, ny, s))  # 移動Aの場合はコスト0. キューの先頭に追加する.
    for dx, dy in warp:  # 移動B
        nx = x + dx
        ny = y + dy
        if 0 <= nx < H and 0 <= ny < W and maze[nx][ny] == '.' and path[nx][ny] > s + 1:
            path[nx][ny] = s + 1
            q.append((nx, ny, s + 1))  # 移動Bの場合はコスト1. キューの最後尾に追加する.
    
ans = path[Dh][Dw] if path[Dh][Dw] < INF else '-1'
print(ans)

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

H, W=map(int, input().split())
ch, cw=map(int, input().split())
dh, dw=map(int, input().split())
ch-=1
cw-=1
dh-=1
dw-=1

grid=["0"]*H
for i in range(H):
    s=input()
    grid[i]=s

Inf=10**12
cost=[[Inf] * W for i in range(H)]

walk=[(0, 1), (0, -1), (-1, 0), (1, 0)]
warp=[]
for i in range(-2, 3):
    for j in range(-2, 3):
        if i==0 and j==0:
            continue
        if (i, j) not in walk:
            warp.append((i, j))

q=deque()
cost=[ch][cw]=0
q.append((ch, cw, 0))

while q:
    x, y, c=q.popleft()
    for dx, dy in walk:
        nx = x+dx
        ny = y+dy
        if 0<= nx < H and 0<= ny < W and grid[nx][ny]=="." and cost[nx][ny]>c:
            cost[nx][ny]=c
            q.appendleft((nx, ny, c))
    
    for dx, dy in warp:
        nx = x+dx
        ny = y+dy
        if 0<= nx < H and 0<= ny < W and grid[nx][ny]=="." and cost[nx][ny]>c+1:
            cost[nx][ny]=c+1
            q.append((nx, ny, c+1))


if cost[dh][dw]==Inf:
    print(-1)
else:
    ans=cost[dh][dw]
    print(ans)

Fixed submission:
from collections import deque


H, W = map(int, input().split())
Ch, Cw = map(lambda x: int(x) - 1, input().split())
Dh, Dw = map(lambda x: int(x) - 1, input().split())
maze = [input() for _ in range(H)]

INF = 10 ** 12
path = [[INF] * W for _ in range(H)]  # path: 各マスへの移動コスト

# walk:移動A, warp:移動B
walk = [(0, 1), (0, -1), (-1, 0), (1, 0)]
warp = [(i, j) for i in range(-2, 3) for j in range(-2, 3) if (i, j) not in [(0, 0)] + walk]

q = deque()
path[Ch][Cw] = 0
q.append((Ch, Cw, 0))

while q:
    x, y, s = q.popleft()
    for dx, dy in walk:  # 移動A
        nx = x + dx
        ny = y + dy
        if 0 <= nx < H and 0 <= ny < W and maze[nx][ny] == '.' and path[nx][ny] > s:
            path[nx][ny] = s
            q.appendleft((nx, ny, s))  # 移動Aの場合はコスト0. キューの先頭に追加する.
    for dx, dy in warp:  # 移動B
        nx = x + dx
        ny = y + dy
        if 0 <= nx < H and 0 <= ny < W and maze[nx][ny] == '.' and path[nx][ny] > s + 1:
            path[nx][ny] = s + 1
            q.append((nx, ny, s + 1))  # 移動Bの場合はコスト1. キューの最後尾に追加する.
    
ans = path[Dh][Dw] if path[Dh][Dw] < INF else '-1'
print(ans)

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

H, W=map(int, input().split())
ch, cw=map(int, input().split())
dh, dw=map(int, input().split())
ch-=1
cw-=1
dh-=1
dw-=1

grid=["0"]*H
for i in range(H):
    s=input()
    grid[i]=s

Inf=10**12
cost=[[Inf] * W for i in range(H)]

walk=[(0, 1), (0, -1), (-1, 0), (1, 0)]
warp=[]
for i in range(-2, 3):
    for j in range(-2, 3):
        if i==0 and j==0:
            continue
        if (i, j) not in walk:
            warp.append((i, j))

q=deque()
cost=[ch][cw]=0
q.append((ch, cw, 0))

while q:
    x, y, c=q.popleft()
    for dx, dy in walk:
        nx = x+dx
        ny = y+dy
        if 0<= nx <= H and 0<= ny <= W and grid[nx][ny]=="." and cost[nx][ny]>c:
            cost[nx][ny]=c
            q.appendleft((nx, ny, c))
    
    for dx, dy in warp:
        nx = x+dx
        ny = y+dy
        if 0<= nx <= H and 0<= ny <= W and grid[nx][ny]=="." and cost[nx][ny]>c+1:
            cost[nx][ny]=c+1
            q.append((nx, ny, c+1))


if cost[dh][dw]==Inf:
    print(-1)
else:
    ans=cost[dh][dw]
    print(ans)

Fixed submission:
from collections import deque


H, W = map(int, input().split())
Ch, Cw = map(lambda x: int(x) - 1, input().split())
Dh, Dw = map(lambda x: int(x) - 1, input().split())
maze = [input() for _ in range(H)]

INF = 10 ** 12
path = [[INF] * W for _ in range(H)]  # path: 各マスへの移動コスト

# walk:移動A, warp:移動B
walk = [(0, 1), (0, -1), (-1, 0), (1, 0)]
warp = [(i, j) for i in range(-2, 3) for j in range(-2, 3) if (i, j) not in [(0, 0)] + walk]

q = deque()
path[Ch][Cw] = 0
q.append((Ch, Cw, 0))

while q:
    x, y, s = q.popleft()
    for dx, dy in walk:  # 移動A
        nx = x + dx
        ny = y + dy
        if 0 <= nx < H and 0 <= ny < W and maze[nx][ny] == '.' and path[nx][ny] > s:
            path[nx][ny] = s
            q.appendleft((nx, ny, s))  # 移動Aの場合はコスト0. キューの先頭に追加する.
    for dx, dy in warp:  # 移動B
        nx = x + dx
        ny = y + dy
        if 0 <= nx < H and 0 <= ny < W and maze[nx][ny] == '.' and path[nx][ny] > s + 1:
            path[nx][ny] = s + 1
            q.append((nx, ny, s + 1))  # 移動Bの場合はコスト1. キューの最後尾に追加する.
    
ans = path[Dh][Dw] if path[Dh][Dw] < INF else '-1'
print(ans)

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

H, W=map(int, input().split())
ch, cw=map(int, input().split())
dh, dw=map(int, input().split())
ch-=1
cw-=1
dh-=1
dw-=1

grid=["0"]*H
for i in range(H):
    s=input()
    grid[i]=s

Inf=10**12
cost=[[Inf] * W for i in range(H)]

walk=[(0, 1), (0, -1), (-1, 0), (1, 0)]
warp=[]
for i in range(-2, 3):
    for j in range(-2, 3):
        if (i, j) not in walk:
            warp.append((i, j))

q=deque()
cost=[ch][cw]=0
q.append((ch, cw, 0))

while q:
    x, y, c=q.popleft()
    for dx, dy in walk:
        nx = x+dx
        ny = y+dy
        if 0<= nx <= H and 0<= ny <= W and grid[nx][ny]=="." and cost[nx][ny]>c:
            cost[nx][ny]=c
            q.appendleft((nx, ny, c))
    
    for dx, dy in warp:
        nx = x+dx
        ny = y+dy
        if 0<= nx <= H and 0<= ny <= W and grid[nx][ny]=="." and cost[nx][ny]>c+1:
            cost[nx][ny]=c+1
            q.append((nx, ny, c+1))


if cost[dh][dw]==Inf:
    print(-1)
else:
    ans=cost[dh][dw]
    print(ans)

Fixed submission:
from collections import deque


H, W = map(int, input().split())
Ch, Cw = map(lambda x: int(x) - 1, input().split())
Dh, Dw = map(lambda x: int(x) - 1, input().split())
maze = [input() for _ in range(H)]

INF = 10 ** 12
path = [[INF] * W for _ in range(H)]  # path: 各マスへの移動コスト

# walk:移動A, warp:移動B
walk = [(0, 1), (0, -1), (-1, 0), (1, 0)]
warp = [(i, j) for i in range(-2, 3) for j in range(-2, 3) if (i, j) not in [(0, 0)] + walk]

q = deque()
path[Ch][Cw] = 0
q.append((Ch, Cw, 0))

while q:
    x, y, s = q.popleft()
    for dx, dy in walk:  # 移動A
        nx = x + dx
        ny = y + dy
        if 0 <= nx < H and 0 <= ny < W and maze[nx][ny] == '.' and path[nx][ny] > s:
            path[nx][ny] = s
            q.appendleft((nx, ny, s))  # 移動Aの場合はコスト0. キューの先頭に追加する.
    for dx, dy in warp:  # 移動B
        nx = x + dx
        ny = y + dy
        if 0 <= nx < H and 0 <= ny < W and maze[nx][ny] == '.' and path[nx][ny] > s + 1:
            path[nx][ny] = s + 1
            q.append((nx, ny, s + 1))  # 移動Bの場合はコスト1. キューの最後尾に追加する.
    
ans = path[Dh][Dw] if path[Dh][Dw] < INF else '-1'
print(ans)