Buggy python submission (verdict: Time Limit Exceeded):
def main():
    import queue
    import sys
    input = sys.stdin.readline

    H, W = list(map(int, input().split()))
    S = list(map(int, input().split()))
    G = list(map(int, input().split()))
    S = [S[0] - 1, S[1] - 1]
    G = [G[0] - 1, G[1] - 1]

    maze = []
    for i in range(H):
        maze.append(input())

    MAX = 1000001
    cost_list = [[MAX] * W for i in range(H)]


    to_walk = queue.Queue()
    to_warp = queue.Queue()


    def walk(z):
        h, w = z
        cost = cost_list[h][w]
        to_warp.put([h, w])
        for [p, q] in [[0, 1], [0, -1], [1, 0], [-1, 0]]:
            a,b=h+p,w+q
            if (0 <= a < H) and (0 <= b < W):
                if maze[a][b] == "." and cost_list[a][b] > cost:
                    cost_list[a][b] = cost
                    to_walk.put([a,b])
                    to_warp.put([a,b])


    def warp(z):
        h, w = z
        cost = cost_list[h][w] + 1
        for [p, q] in [[-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]]:
            a,b=h+p,w+q
            if (0 <= a < H) and (0 <= b < W):
                if maze[a][b] == "." and cost_list[a][b] > cost:
                    cost_list[a][b] = cost
                    to_walk.put([a, b])


    to_walk.put(S)
    cost_list[S[0]][S[1]] = 0

    while True:
        while not to_walk.empty():
            walk(to_walk.get())
        while not to_warp.empty():
            warp(to_warp.get())
        if to_walk.empty() and to_warp.empty():
            break

    if cost_list[G[0]][G[1]] == MAX:
        print(-1)
    else:
        print(cost_list[G[0]][G[1]])

if __name__ == "__main__":
    main()



Fixed submission:
import queue
h,w=map(int,input().split())
sy,sx=map(int,input().split())
gy,gx=map(int,input().split())
s=[input() for _ in range(h)]
q=queue.deque([[sy-1,sx-1]])
q2=[[sy-1,sx-1]]
q3=[]
inf=10**7
dist=[[inf for _ in range(w)] for _ in range(h)]
d=[[1,0],[0,1],[-1,0],[0,-1]]
dist[sy-1][sx-1]=0

while q:
    y,x=q.pop()
    for dy,dx in d:
        ny,nx=y+dy,x+dx
        if 0<=ny<h and 0<=nx<w and s[ny][nx]!='#' and dist[ny][nx]==inf:
            dist[ny][nx]=min(dist[y][x],dist[ny][nx])
            q.append([ny,nx])
            q2.append([ny,nx])
    if not q:
        for y,x in q2:
            for dy in range(-2,3):
                for dx in range(-2,3):
                    ny,nx=y+dy,x+dx
                    if 0<=ny<h and 0<=nx<w and s[ny][nx]!='#' and dist[ny][nx]==inf:
                        dist[ny][nx]=min(dist[y][x]+1,dist[ny][nx])
                        q.append([ny,nx])
                        q3.append([ny,nx])
        q2=q3
        q3=[]
print(dist[gy-1][gx-1] if dist[gy-1][gx-1]!=inf else -1)

Buggy python submission (verdict: Time Limit Exceeded):
import queue

H, W = list(map(int, input().split()))
S = list(map(int, input().split()))
G = list(map(int, input().split()))
S = [S[0] - 1, S[1] - 1]
G = [G[0] - 1, G[1] - 1]

maze = []
for i in range(H):
    maze.append(input())

MAX = 1000001
cost_list = [[MAX] * W for i in range(H)]


to_walk = queue.Queue()
to_warp = queue.Queue()


def walk(z):
    h, w = z
    cost = cost_list[h][w]
    to_warp.put([h, w])
    for [p, q] in [[0, 1], [0, -1], [1, 0], [-1, 0]]:
        a,b=h+p,w+q
        if (0 <= a < H) and (0 <= b < W):
            if maze[a][b] == "." and cost_list[a][b] > cost:
                cost_list[a][b] = cost
                to_walk.put([a,b])
                to_warp.put([a,b])


def warp(z):
    h, w = z
    cost = cost_list[h][w] + 1
    for [p, q] in [[-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]]:
        a,b=h+p,w+q
        if (0 <= a < H) and (0 <= b < W):
            if maze[a][b] == "." and cost_list[a][b] > cost:
                cost_list[a][b] = cost
                to_walk.put([a, b])


to_walk.put(S)
cost_list[S[0]][S[1]] = 0

while True:
    while not to_walk.empty():
        walk(to_walk.get())
    while not to_warp.empty():
        warp(to_warp.get())
    if to_walk.empty() and to_warp.empty():
        break

if cost_list[G[0]][G[1]] == MAX:
    print(-1)
else:
    print(cost_list[G[0]][G[1]])



Fixed submission:
import queue
h,w=map(int,input().split())
sy,sx=map(int,input().split())
gy,gx=map(int,input().split())
s=[input() for _ in range(h)]
q=queue.deque([[sy-1,sx-1]])
q2=[[sy-1,sx-1]]
q3=[]
inf=10**7
dist=[[inf for _ in range(w)] for _ in range(h)]
d=[[1,0],[0,1],[-1,0],[0,-1]]
dist[sy-1][sx-1]=0

while q:
    y,x=q.pop()
    for dy,dx in d:
        ny,nx=y+dy,x+dx
        if 0<=ny<h and 0<=nx<w and s[ny][nx]!='#' and dist[ny][nx]==inf:
            dist[ny][nx]=min(dist[y][x],dist[ny][nx])
            q.append([ny,nx])
            q2.append([ny,nx])
    if not q:
        for y,x in q2:
            for dy in range(-2,3):
                for dx in range(-2,3):
                    ny,nx=y+dy,x+dx
                    if 0<=ny<h and 0<=nx<w and s[ny][nx]!='#' and dist[ny][nx]==inf:
                        dist[ny][nx]=min(dist[y][x]+1,dist[ny][nx])
                        q.append([ny,nx])
                        q3.append([ny,nx])
        q2=q3
        q3=[]
print(dist[gy-1][gx-1] if dist[gy-1][gx-1]!=inf else -1)

Buggy python submission (verdict: Time Limit Exceeded):
import queue

H, W = list(map(int, input().split()))
S = list(map(int, input().split()))
G = list(map(int, input().split()))
S = [S[0] - 1, S[1] - 1]
G = [G[0] - 1, G[1] - 1]

maze = []
for i in range(H):
    maze.append(input())

MAX = 1000001
cost_list = [[MAX] * W for i in range(H)]


to_walk = queue.Queue()
to_warp = queue.Queue()


def walk(z):
    h, w = z
    cost = cost_list[h][w]
    to_warp.put([h, w])
    for [p, q] in [[0, 1], [0, -1], [1, 0], [-1, 0]]:
        if (0 <= h + p < H) and (0 <= w + q < W):
            if maze[h + p][w + q] == "." and cost_list[h + p][w + q] > cost:
                cost_list[h + p][w + q] = cost
                to_walk.put([h + p, w + q])
                to_warp.put([h + p, w + q])


def warp(z):
    h, w = z
    cost = cost_list[h][w] + 1
    for [p, q] in [[-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]]:
        if (0 <= h + p < H) and (0 <= w + q < W):
            if maze[h + p][w + q] == "." and cost_list[h + p][w + q] > cost:
                cost_list[h + p][w + q] = cost
                to_walk.put([h + p, w + q])


to_walk.put(S)
cost_list[S[0]][S[1]] = 0

while True:
    while not to_walk.empty():
        walk(to_walk.get())
    while not to_warp.empty():
        warp(to_warp.get())
    if to_walk.empty() and to_warp.empty():
        break

if cost_list[G[0]][G[1]] == MAX:
    print(-1)
else:
    print(cost_list[G[0]][G[1]])



Fixed submission:
import queue
h,w=map(int,input().split())
sy,sx=map(int,input().split())
gy,gx=map(int,input().split())
s=[input() for _ in range(h)]
q=queue.deque([[sy-1,sx-1]])
q2=[[sy-1,sx-1]]
q3=[]
inf=10**7
dist=[[inf for _ in range(w)] for _ in range(h)]
d=[[1,0],[0,1],[-1,0],[0,-1]]
dist[sy-1][sx-1]=0

while q:
    y,x=q.pop()
    for dy,dx in d:
        ny,nx=y+dy,x+dx
        if 0<=ny<h and 0<=nx<w and s[ny][nx]!='#' and dist[ny][nx]==inf:
            dist[ny][nx]=min(dist[y][x],dist[ny][nx])
            q.append([ny,nx])
            q2.append([ny,nx])
    if not q:
        for y,x in q2:
            for dy in range(-2,3):
                for dx in range(-2,3):
                    ny,nx=y+dy,x+dx
                    if 0<=ny<h and 0<=nx<w and s[ny][nx]!='#' and dist[ny][nx]==inf:
                        dist[ny][nx]=min(dist[y][x]+1,dist[ny][nx])
                        q.append([ny,nx])
                        q3.append([ny,nx])
        q2=q3
        q3=[]
print(dist[gy-1][gx-1] if dist[gy-1][gx-1]!=inf else -1)