Buggy python submission (verdict: Time Limit Exceeded):
from collections import deque
h, w = map(int, input().split())
c_h, c_w = map(int, input().split())
d_h, d_w = map(int, input().split())
#スタートとゴールの座標を設定
start_h = c_h - 1
start_w = c_w - 1
goal_h = d_h - 1
goal_w = d_w - 1
#迷路の読み込み
maze = [input() for _ in range(h)]
inf = float("inf")
dist = [[inf] * w for _ in range(h)]



def bfs(x, y):
    dist[x][y] = 0
    q_walk = deque()
    q_warp = deque()
    q_walk.append((x, y))
    while len(q_walk) > 0:
        x, y = q_walk.popleft() 
        q_warp.append((x, y))
        d = dist[x][y]
        for dx, dy in [(0,1),(1,0),(0,-1),(-1,0)]:
            nx = x + dx
            ny = y + dy 
            if not 0 <= nx < h or not 0 <= ny < w:
                continue
            if maze[nx][ny] == "#":
                continue
            if dist[nx][ny] <= d:
                continue
            dist[nx][ny] = d           
            q_walk.append((nx, ny))
        if len(q_walk) == 0:
            while len(q_warp) > 0:
                x2, y2 = q_warp.popleft()
                for dxx in range(-2, 3):
                    for dyy in range(-2, 3):
                        nxx = x2 + dxx
                        nyy = y2 + dyy 
                        if not 0 <= nxx < h or not 0 <= nyy < w:
                            continue
                        if maze[nxx][nyy] == "#":
                            continue
                        if dist[nxx][nyy] <= d+1:
                            continue
                        dist[nxx][nyy] = d+1
                        q_walk.append((nxx, nyy))
                



bfs(start_h, start_w)
if dist[goal_h][goal_w] == inf:
    print("-1")
else:
    print(dist[goal_h][goal_w])    

Fixed submission:
from collections import deque
h, w = map(int, input().split())
c_h, c_w = map(int, input().split())
d_h, d_w = map(int, input().split())
#スタートとゴールの座標を設定
start_h = c_h - 1
start_w = c_w - 1
goal_h = d_h - 1
goal_w = d_w - 1
#迷路の読み込み
maze = [input() for _ in range(h)]
inf = float("inf")
dist = [[inf] * w for _ in range(h)]



def bfs(x, y):
    dist[x][y] = 0
    q = deque()
    q.append((x, y))
    while q:
        x, y = q.popleft() 
        d = dist[x][y]
        for dx, dy in [(0,1),(1,0),(0,-1),(-1,0)]:
            nx = x + dx
            ny = y + dy 
            if not 0 <= nx < h or not 0 <= ny < w:
                continue
            if maze[nx][ny] == "#":
                continue
            if dist[nx][ny] <= d:
                continue
            dist[nx][ny] = d           
            q.appendleft((nx, ny))

        for dxx in range(-2, 3):
            for dyy in range(-2, 3):
                 nxx = x + dxx
                 nyy = y + dyy 
                 if not 0 <= nxx < h or not 0 <= nyy < w:
                    continue
                 if maze[nxx][nyy] == "#":
                    continue
                 if dist[nxx][nyy] <= d+1:
                    continue
                 dist[nxx][nyy] = d+1
                 q.append((nxx, nyy))
                



bfs(start_h, start_w)
if dist[goal_h][goal_w] == inf:
    print("-1")
else:
    print(dist[goal_h][goal_w])

Buggy python submission (verdict: Runtime Error):
from collections import deque
h, w = map(int, input().split())
c_h, c_w = map(int, input().split())
d_h, d_w = map(int, input().split())
#スタートとゴールの座標を設定
start_h = c_h - 1
start_w = c_w - 1
goal_h = d_h - 1
goal_w = d_w - 1
#迷路の読み込み
maze = [input() for _ in range(h)]
inf = float("inf")
dist = [[inf] * w for _ in range(h)]



def bfs(x, y):
    dist[x][y] = 0
    q_walk = deque()
    q_warp = deque()
    q_walk.append((x, y))
    while q_walk > 0:
        x, y = q_walk.popleft() 
        q_warp.append((x, y))
        d = dist[x][y]
        for dx, dy in [(0,1),(1,0),(0,-1),(-1,0)]:
            nx = x + dx
            ny = y + dy 
            if not 0 <= nx < h or not 0 <= ny < w:
                continue
            if maze[nx][ny] == "#":
                continue
            if dist[nx][ny] <= d:
                continue
            dist[nx][ny] = d           
            q_walk.append((nx, ny))
        if len(q_wark) == 0:
            while len(q_warp) > 0:
                x2, y2 = q_warp.popleft()
                for dxx in range(-2, 3):
                    for dyy in range(-2, 3):
                        nxx = x2 + dxx
                        nyy = y2 + dyy 
                        if not 0 <= nxx < h or not 0 <= nyy < w:
                            continue
                        if maze[nxx][nyy] == "#":
                            continue
                        if dist[nxx][nyy] <= d+1:
                            continue
                        dist[nxx][nyy] = d+1
                        q_warp.append((nxx, nyy))
                



bfs(start_h, start_w)
if dist[goal_h][goal_w] == inf:
    print("-1")
else:
    print(dist[goal_h][goal_w])    



Fixed submission:
from collections import deque
h, w = map(int, input().split())
c_h, c_w = map(int, input().split())
d_h, d_w = map(int, input().split())
#スタートとゴールの座標を設定
start_h = c_h - 1
start_w = c_w - 1
goal_h = d_h - 1
goal_w = d_w - 1
#迷路の読み込み
maze = [input() for _ in range(h)]
inf = float("inf")
dist = [[inf] * w for _ in range(h)]



def bfs(x, y):
    dist[x][y] = 0
    q = deque()
    q.append((x, y))
    while q:
        x, y = q.popleft() 
        d = dist[x][y]
        for dx, dy in [(0,1),(1,0),(0,-1),(-1,0)]:
            nx = x + dx
            ny = y + dy 
            if not 0 <= nx < h or not 0 <= ny < w:
                continue
            if maze[nx][ny] == "#":
                continue
            if dist[nx][ny] <= d:
                continue
            dist[nx][ny] = d           
            q.appendleft((nx, ny))

        for dxx in range(-2, 3):
            for dyy in range(-2, 3):
                 nxx = x + dxx
                 nyy = y + dyy 
                 if not 0 <= nxx < h or not 0 <= nyy < w:
                    continue
                 if maze[nxx][nyy] == "#":
                    continue
                 if dist[nxx][nyy] <= d+1:
                    continue
                 dist[nxx][nyy] = d+1
                 q.append((nxx, nyy))
                



bfs(start_h, start_w)
if dist[goal_h][goal_w] == inf:
    print("-1")
else:
    print(dist[goal_h][goal_w])

Buggy python submission (verdict: Time Limit Exceeded):
from collections import deque
h, w = map(int, input().split())
c_h, c_w = map(int, input().split())
d_h, d_w = map(int, input().split())
#スタートとゴールの座標を設定
start_h = c_h - 1
start_w = c_w - 1
goal_h = d_h - 1
goal_w = d_w - 1
#迷路の読み込み
maze = [input() for _ in range(h)]
inf = float("inf")
dist = [[inf] * w for _ in range(h)]



def bfs(x, y):
    dist[x][y] = 0
    q = deque()
    q.append((x, y))
    while q:
        x, y = q.popleft() 
        d = dist[x][y]
        for dx, dy in [(0,1),(1,0),(0,-1),(-1,0)]:
            nx = x + dx
            ny = y + dy 
            if not 0 <= nx < h or not 0 <= ny < w:
                continue
            if maze[nx][ny] == "#":
                continue
            if dist[nx][ny] <= d:
                continue
            dist[nx][ny] = d           
            q.appendleft((nx, ny))

        for dxx in range(-2, 3):
            for dyy in range(-2, 3):
                 nxx = x + dxx
                 nyy = y + dyy 
                 if not 0 <= nxx < h or not 0 <= nyy < w:
                    continue
                 if maze[nxx][nyy] == "#":
                    continue
                 if dist[nxx][nyy] <= d+1:
                    continue
                 dist[nxx][nyy] = d+1
                 q.append((nxx, nyy))
                



bfs(start_h, start_w)
if dist[goal_h][goal_w] == inf:
    print("-1")
else:
    print(dist[goal_h][goal_w])    

Fixed submission:
from collections import deque
h, w = map(int, input().split())
c_h, c_w = map(int, input().split())
d_h, d_w = map(int, input().split())
#スタートとゴールの座標を設定
start_h = c_h - 1
start_w = c_w - 1
goal_h = d_h - 1
goal_w = d_w - 1
#迷路の読み込み
maze = [input() for _ in range(h)]
inf = float("inf")
dist = [[inf] * w for _ in range(h)]



def bfs(x, y):
    dist[x][y] = 0
    q = deque()
    q.append((x, y))
    while q:
        x, y = q.popleft() 
        d = dist[x][y]
        for dx, dy in [(0,1),(1,0),(0,-1),(-1,0)]:
            nx = x + dx
            ny = y + dy 
            if not 0 <= nx < h or not 0 <= ny < w:
                continue
            if maze[nx][ny] == "#":
                continue
            if dist[nx][ny] <= d:
                continue
            dist[nx][ny] = d           
            q.appendleft((nx, ny))

        for dxx in range(-2, 3):
            for dyy in range(-2, 3):
                 nxx = x + dxx
                 nyy = y + dyy 
                 if not 0 <= nxx < h or not 0 <= nyy < w:
                    continue
                 if maze[nxx][nyy] == "#":
                    continue
                 if dist[nxx][nyy] <= d+1:
                    continue
                 dist[nxx][nyy] = d+1
                 q.append((nxx, nyy))
                



bfs(start_h, start_w)
if dist[goal_h][goal_w] == inf:
    print("-1")
else:
    print(dist[goal_h][goal_w])