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

H,W = map(int,input().split())
C_pos=list(map(lambda x:int(x)-1,input().split()))
D_pos=list(map(lambda x:int(x)-1,input().split()))
Grid=[[c for c in input()] for _ in range(H)]

Dist=[[float("inf")]*W for _ in range(H)]

DX=[0,0,1,-1]

Q=deque()
Q.append((C_pos[0],C_pos[1]))
Dist[C_pos[0]][C_pos[1]]=0

while Q:
    cx,cy = Q.pop()

    for dx,dy in zip(DX,reversed(DX)):
        nx=cx+dx
        ny=cy+dy

        if 0<=nx<H and 0<=ny<W and Grid[nx][ny]=="." and Dist[nx][ny]>Dist[cx][cy]:
            Dist[nx][ny]=Dist[cx][cy]
            Q.append((nx,ny))


    for dx in range(-2,3):
        for dy in range(-2,3):
            nx=cx+dx
            ny=cy+dy
            if dx==0 and dy==0:
                continue

            if 0<=nx<H and 0<=ny<W and Grid[nx][ny]=="." and Dist[nx][ny]==float("inf"):
                Dist[nx][ny]=Dist[cx][cy]+1
                Q.appendleft((nx,ny))


ans=Dist[D_pos[0]][D_pos[1]]
if ans==float("inf"):
    print(-1)
else:
    print(ans)




Fixed submission:
from collections import deque
import sys
input=sys.stdin.readline
H,W = map(int,input().split())
C_pos=list(map(lambda x:int(x)-1,input().split()))
D_pos=list(map(lambda x:int(x)-1,input().split()))
Grid=[[c for c in input()] for _ in range(H)]
Dist=[[float("inf")]*W for _ in range(H)]

DX=[0,0,1,-1]
DY=[1,-1,0,0]

Q=deque()
Q.append((C_pos[0],C_pos[1]))
DX=[-1,1,0,0]
visited=set()
prev_visited=set()

dist=0
while True:
    prev_visited=set(v for v in Q)
    if len(Q)==0:
        print(-1)
        exit()

    #できる限りbfs
    while Q:
        cx,cy=Q.pop()
        if cx==D_pos[0] and cy==D_pos[1]:
            print(dist)
            exit()

        visited.add((cx,cy))
        for dx,dy in zip(DX,reversed(DX)):
            nx = cx+dx
            ny=cy+dy
            if 0<=nx<H and 0<=ny<W and Grid[nx][ny]=="." and (nx,ny) not in visited:
                visited.add((nx,ny))
                prev_visited.add((nx,ny))
                Dist[nx][ny]=dist
                Q.append((nx,ny))
                if nx==D_pos[0] and ny==D_pos[1]:
                    print(dist)
                    exit()

    Q=deque()
    for cx,cy in prev_visited:
        for dx in range(-2,3):
            for dy in range(-2,3):
                if dx==0 and dy==0:
                    continue
                nx = cx+dx
                ny=cy+dy
                if (nx,ny) in visited:
                    continue
                if 0<=nx<H and 0<=ny<W and Grid[nx][ny]==".":
                    Q.append((nx,ny))
    dist+=1

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

H,W = map(int,input().split())
C_pos=list(map(lambda x:int(x)-1,input().split()))

C_pos=(C_pos[0],C_pos[1])

D_pos=list(map(lambda x:int(x)-1,input().split()))

Grid=[[c for c in input()] for _ in range(H)]

Dist=[[float("inf")]*W for _ in range(H)]

Dist[C_pos[0]][C_pos[1]]=0


Q=[]
heapq.heappush(Q,(0,C_pos[0],C_pos[1]))

DX=[-1,1,0,0]
while Q:
    #上下左右の道
    dist,cx,cy=heapq.heappop(Q)

    if cx==D_pos[0] and cy==D_pos[1]:
        break

    for dx,dy in zip(DX,reversed(DX)):
        nx = cx+dx
        ny=cy+dy
        if 0<=nx<H and 0<=ny<W and Grid[nx][ny]==".":
            if Dist[nx][ny]>dist:
                Dist[nx][ny]=dist
                Q.append((dist,nx,ny))
    #ワープ
    for dx in range(-2,3):
        for dy in range(-2,3):
            if dx==0 and dy==0:
                continue
            nx = cx+dx
            ny=cy+dy
            if 0<=nx<H and 0<=ny<W and Grid[nx][ny]==".":
                if Dist[nx][ny]>dist+1:
                    Dist[nx][ny]=dist+1
                    Q.append((dist+1,nx,ny))


#print(Dist)
ans=Dist[D_pos[0]][D_pos[1]]
if ans==float("inf"):
    print(-1)
else:
    print(ans)


Fixed submission:
from collections import deque
import sys
input=sys.stdin.readline
H,W = map(int,input().split())
C_pos=list(map(lambda x:int(x)-1,input().split()))
D_pos=list(map(lambda x:int(x)-1,input().split()))
Grid=[[c for c in input()] for _ in range(H)]
Dist=[[float("inf")]*W for _ in range(H)]

DX=[0,0,1,-1]
DY=[1,-1,0,0]

Q=deque()
Q.append((C_pos[0],C_pos[1]))
DX=[-1,1,0,0]
visited=set()
prev_visited=set()

dist=0
while True:
    prev_visited=set(v for v in Q)
    if len(Q)==0:
        print(-1)
        exit()

    #できる限りbfs
    while Q:
        cx,cy=Q.pop()
        if cx==D_pos[0] and cy==D_pos[1]:
            print(dist)
            exit()

        visited.add((cx,cy))
        for dx,dy in zip(DX,reversed(DX)):
            nx = cx+dx
            ny=cy+dy
            if 0<=nx<H and 0<=ny<W and Grid[nx][ny]=="." and (nx,ny) not in visited:
                visited.add((nx,ny))
                prev_visited.add((nx,ny))
                Dist[nx][ny]=dist
                Q.append((nx,ny))
                if nx==D_pos[0] and ny==D_pos[1]:
                    print(dist)
                    exit()

    Q=deque()
    for cx,cy in prev_visited:
        for dx in range(-2,3):
            for dy in range(-2,3):
                if dx==0 and dy==0:
                    continue
                nx = cx+dx
                ny=cy+dy
                if (nx,ny) in visited:
                    continue
                if 0<=nx<H and 0<=ny<W and Grid[nx][ny]==".":
                    Q.append((nx,ny))
    dist+=1