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

H,W=map(int,input().split())
sy,sx=map(int,input().split())
gy,gx=map(int,input().split())
field=[list(input()) for _ in range(H)]
sy,sx,gy,gx=sy-1,sx-1,gy-1,gx-1

Walk=[[1,0],[0,1],[-1,0],[0,-1]]
Warp=[[i,j] for i in range(-2,3) for j in range(-2,3)] 

dist=[[-1]*W for _ in range(H)]
que=deque()
dist[sy][sx]=0
que.append([sy,sx])

while que:
    y,x=que.popleft()
    for walk in Walk:
        nx,ny=x+walk[0],y+walk[1]
        if nx<0 or nx>=W or ny<0 or ny>=H: continue
        if field[ny][nx]=="#": continue
        if dist[ny][nx]!=dist[y][x]:
            dist[ny][nx]=dist[y][x]
            que.appendleft([ny,nx])
    
    for warp in Warp:
        nx,ny=x+warp[0],y+warp[1]
        if nx<0 or nx>=W or ny<0 or ny>=H: continue
        if field[ny][nx]=="#": continue
        if dist[ny][nx]==-1:
            dist[ny][nx]=dist[y][x]+1
            que.append([ny,nx])

print(dist[gy][gx])


Fixed submission:
from collections import deque

H,W=map(int,input().split())
sy,sx=map(int,input().split())
gy,gx=map(int,input().split())
field=[list(input()) for _ in range(H)]
sy,sx,gy,gx=sy-1,sx-1,gy-1,gx-1

Walk=[[1,0],[0,1],[-1,0],[0,-1]]
Warp=[[i,j] for i in range(-2,3) for j in range(-2,3)] 

dist=[[-1]*W for _ in range(H)]
que=deque()
dist[sy][sx]=0
que.append([sy,sx])

while que:
    y,x=que.popleft()
    for walk in Walk:
        nx,ny=x+walk[0],y+walk[1]
        if nx<0 or nx>=W or ny<0 or ny>=H: continue
        if field[ny][nx]=="#": continue
        if dist[ny][nx]!=dist[y][x]:
            dist[ny][nx]=dist[y][x]
            que.appendleft([ny,nx])
    
    for warp in Warp:
        nx,ny=x+warp[0],y+warp[1]
        if nx<0 or nx>=W or ny<0 or ny>=H: continue
        if field[ny][nx]=="#": continue
        if dist[ny][nx]==-1:
            dist[ny][nx]=dist[y][x]+1
            que.append([ny,nx])

print(dist[gy][gx])

Buggy python submission (verdict: Runtime Error):
H,W=map(int,input().split())
C=list(map(int,input().split()))
C[0]+=1
C[1]+=1
D=list(map(int,input().split()))
D[0]+=1
D[1]+=1
S=["#"*(W+4)]
S.append("#"*(W+4))
for _ in range(H):
    tmp=input()
    tmp="##"+tmp+"##"
    S.append(tmp)
S.append("#"*(W+4))
S.append("#"*(W+4))

def walk(k,alk,x,y):
    global found
    if x==D[0] and y==D[1]:
        S[x]=S[x][:y]+"{}".format(k)+S[x][y+1:]
        found=True
        return 0
    if S[x][y]==".":
        alk.append([x,y])
        S[x]=S[x][:y]+"{}".format(k)+S[x][y+1:]
        walk(k,alk,x-1,y)
        walk(k,alk,x,y-1)
        walk(k,alk,x+1,y)
        walk(k,alk,x,y+1)

def warp(k,arp,x,y):
    for i in range(-2,3):
        for j in range(-2,3):
            if S[x+i][y+j]==".":
                arp.append([x+i,y+j])
                S[x+i]=S[x+i][:y+j]+"{}".format(k)+S[x+i][y+j+1:]

k=0
alk=[]
arp=[[C[0],C[1]]]
found=False
while not found:
    alk=arp
    for i in range(len(arp)):
        x,y=arp[i][0],arp[i][1]
        walk(k,alk,x,y)
        if found:
            print(k)
            break
    if found:
        break
    k+=1
    arp=[]
    for i in range(len(alk)):
        x,y=alk[i][0],alk[i][1]
        warp(k,arp,x,y)
    if len(arp)==0:
        print(-1)
        break


Fixed submission:
from collections import deque

H,W=map(int,input().split())
sy,sx=map(int,input().split())
gy,gx=map(int,input().split())
field=[list(input()) for _ in range(H)]
sy,sx,gy,gx=sy-1,sx-1,gy-1,gx-1

Walk=[[1,0],[0,1],[-1,0],[0,-1]]
Warp=[[i,j] for i in range(-2,3) for j in range(-2,3)] 

dist=[[-1]*W for _ in range(H)]
que=deque()
dist[sy][sx]=0
que.append([sy,sx])

while que:
    y,x=que.popleft()
    for walk in Walk:
        nx,ny=x+walk[0],y+walk[1]
        if nx<0 or nx>=W or ny<0 or ny>=H: continue
        if field[ny][nx]=="#": continue
        if dist[ny][nx]!=dist[y][x]:
            dist[ny][nx]=dist[y][x]
            que.appendleft([ny,nx])
    
    for warp in Warp:
        nx,ny=x+warp[0],y+warp[1]
        if nx<0 or nx>=W or ny<0 or ny>=H: continue
        if field[ny][nx]=="#": continue
        if dist[ny][nx]==-1:
            dist[ny][nx]=dist[y][x]+1
            que.append([ny,nx])

print(dist[gy][gx])