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

S=[]
for i in range(H):
  s=list(input())
  S.append([10**10 if i =="." else -1 for i in s])
visit=[[False for i in range(W)] for j in range(H)]

dq = deque()
dq.append((Ch,Cw,0))
S[Ch][Cw]=0
counter=0

while dq:
  a=dq.popleft()
  if visit[a[0]][a[1]]==True:
    continue
  elif S[a[0]][a[1]]==counter:
    visit[a[0]][a[1]]=True
  elif a[2]==counter+1:
    visit[a[0]][a[1]]=True
    counter+=1
  for i in range(5):
    for j in range(5):
      if a[0]-2+i>=0 and a[0]-2+i<H and a[1]-2+j>=0 and a[1]-2+j<W:
        if abs(i-2)+abs(j-2)==1 and S[a[0]][a[1]]<S[a[0]-2+i][a[1]-2+j] and visit[a[0]-2+i][a[1]-2+j]==False:
          S[a[0]-2+i][a[1]-2+j]=counter
          dq.appendleft((a[0]-2+i,a[1]-2+j,counter))
        elif S[a[0]][a[1]]+1<S[a[0]-2+i][a[1]-2+j] and visit[a[0]-2+i][a[1]-2+j]==False:
          S[a[0]-2+i][a[1]-2+j]=counter+1
          dq.append((a[0]-2+i,a[1]-2+j,counter+1))
  #print(visit,counter,a,dq,"\n")
if S[Dh][Dw]==10**10:
  print(-1)
else:
  print(S[Dh][Dw])


Fixed submission:
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

S=[]
for i in range(H):
  s=list(input())
  S.append([10**10 if i =="." else -1 for i in s])
visit=[[False for i in range(W)] for j in range(H)]

dq = deque()
dq.append((Ch,Cw,0))
S[Ch][Cw]=0
counter=0

while dq:
  a=dq.popleft()
  if visit[a[0]][a[1]]==True:
    continue
  elif S[a[0]][a[1]]==counter:
    visit[a[0]][a[1]]=True
  elif a[2]==counter+1:
    visit[a[0]][a[1]]=True
    counter+=1
  for i in range(5):
    for j in range(5):
      if a[0]-2+i>=0 and a[0]-2+i<H and a[1]-2+j>=0 and a[1]-2+j<W:
        if abs(i-2)+abs(j-2)==1 and S[a[0]][a[1]]<S[a[0]-2+i][a[1]-2+j] and visit[a[0]-2+i][a[1]-2+j]==False:
          S[a[0]-2+i][a[1]-2+j]=counter
          dq.appendleft((a[0]-2+i,a[1]-2+j,counter))
        elif S[a[0]][a[1]]+1<S[a[0]-2+i][a[1]-2+j] and visit[a[0]-2+i][a[1]-2+j]==False:
          S[a[0]-2+i][a[1]-2+j]=counter+1
          dq.append((a[0]-2+i,a[1]-2+j,counter+1))
  #print(visit,counter,a,dq,"\n")
if S[Dh][Dw]==10**10:
  print(-1)
else:
  print(S[Dh][Dw])

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

S=[]
for i in range(H):
  s=list(input())
  S.append([10**10 if i =="." else -1 for i in s])

dq = deque()
dq.append((Ch,Cw))
S[Ch][Cw]=0

while dq:
  a=dq.pop()
  for i in range(5):
    for j in range(5):
      if a[0]-2+i>=0 and a[0]-2+i<H and a[1]-2+j>=0 and a[1]-2+j<W:
        if abs(i-2)+abs(j-2)==1 and S[a[0]][a[1]]<S[a[0]-2+i][a[1]-2+j]:
          S[a[0]-2+i][a[1]-2+j]=S[a[0]][a[1]]
          dq.appendleft((a[0]-2+i,a[1]-2+j))
        elif S[a[0]][a[1]]+1<S[a[0]-2+i][a[1]-2+j]:
          S[a[0]-2+i][a[1]-2+j]=S[a[0]][a[1]]+1
          dq.append((a[0]-2+i,a[1]-2+j))
      

if S[Dh][Dw]==10**10:
  print(-1)
else:
  print(S[Dh][Dw])

Fixed submission:
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

S=[]
for i in range(H):
  s=list(input())
  S.append([10**10 if i =="." else -1 for i in s])
visit=[[False for i in range(W)] for j in range(H)]

dq = deque()
dq.append((Ch,Cw,0))
S[Ch][Cw]=0
counter=0

while dq:
  a=dq.popleft()
  if visit[a[0]][a[1]]==True:
    continue
  elif S[a[0]][a[1]]==counter:
    visit[a[0]][a[1]]=True
  elif a[2]==counter+1:
    visit[a[0]][a[1]]=True
    counter+=1
  for i in range(5):
    for j in range(5):
      if a[0]-2+i>=0 and a[0]-2+i<H and a[1]-2+j>=0 and a[1]-2+j<W:
        if abs(i-2)+abs(j-2)==1 and S[a[0]][a[1]]<S[a[0]-2+i][a[1]-2+j] and visit[a[0]-2+i][a[1]-2+j]==False:
          S[a[0]-2+i][a[1]-2+j]=counter
          dq.appendleft((a[0]-2+i,a[1]-2+j,counter))
        elif S[a[0]][a[1]]+1<S[a[0]-2+i][a[1]-2+j] and visit[a[0]-2+i][a[1]-2+j]==False:
          S[a[0]-2+i][a[1]-2+j]=counter+1
          dq.append((a[0]-2+i,a[1]-2+j,counter+1))
  #print(visit,counter,a,dq,"\n")
if S[Dh][Dw]==10**10:
  print(-1)
else:
  print(S[Dh][Dw])

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

S=[]
for i in range(H):
  s=list(input())
  S.append([10^10 if i =="." else -1 for i in s])

dq = deque()
dq.append((Ch,Cw))
S[Ch][Cw]=0

while dq:
  a=dq.pop()
  for i in range(5):
    for j in range(5):
      if a[0]-2+i>=0 and a[0]-2+i<H and a[1]-2+j>=0 and a[1]-2+j<W and abs(i-2)+abs(j-2)==1:
        S[a[0]-2+i][a[1]-2+j]=min(S[a[0]][a[1]],S[a[0]-2+i][a[1]-2+j])
        dq.appendleft((a[0]-2+i,a[1]-2+j))
      elif a[0]-2+i>=0 and a[0]-2+i<H and a[1]-2+j>=0 and a[1]-2+j<W:
        S[a[0]-2+i][a[1]-2+j]=min(S[a[0]][a[1]]+1,S[a[0]-2+i][a[1]-2+j])
        dq.append((a[0]-2+i,a[1]-2+j))

print(S[Dh][Dw])

Fixed submission:
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

S=[]
for i in range(H):
  s=list(input())
  S.append([10**10 if i =="." else -1 for i in s])
visit=[[False for i in range(W)] for j in range(H)]

dq = deque()
dq.append((Ch,Cw,0))
S[Ch][Cw]=0
counter=0

while dq:
  a=dq.popleft()
  if visit[a[0]][a[1]]==True:
    continue
  elif S[a[0]][a[1]]==counter:
    visit[a[0]][a[1]]=True
  elif a[2]==counter+1:
    visit[a[0]][a[1]]=True
    counter+=1
  for i in range(5):
    for j in range(5):
      if a[0]-2+i>=0 and a[0]-2+i<H and a[1]-2+j>=0 and a[1]-2+j<W:
        if abs(i-2)+abs(j-2)==1 and S[a[0]][a[1]]<S[a[0]-2+i][a[1]-2+j] and visit[a[0]-2+i][a[1]-2+j]==False:
          S[a[0]-2+i][a[1]-2+j]=counter
          dq.appendleft((a[0]-2+i,a[1]-2+j,counter))
        elif S[a[0]][a[1]]+1<S[a[0]-2+i][a[1]-2+j] and visit[a[0]-2+i][a[1]-2+j]==False:
          S[a[0]-2+i][a[1]-2+j]=counter+1
          dq.append((a[0]-2+i,a[1]-2+j,counter+1))
  #print(visit,counter,a,dq,"\n")
if S[Dh][Dw]==10**10:
  print(-1)
else:
  print(S[Dh][Dw])

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

S=[]
for i in range(H):
  s=list(input())
  S.append([-1 if i =="." else -2 for i in s])

dq = deque()
dq.append((Ch,Cw))
S[Ch][Cw]=0

while dq:
  a=dq.pop()
  for i in range(5):
    for j in range(5):
      if a[0]-2+i>=0 and a[0]-2+i<H and a[1]-2+j>=0 and a[1]-2+j<W and abs(i-2)+abs(j-2)==1 and (S[a[0]-2+i][a[1]-2+j]==-1 or S[a[0]-2+i][a[1]-2+j]>S[a[0]][a[1]]):
        S[a[0]-2+i][a[1]-2+j]=S[a[0]][a[1]]
        dq.appendleft((a[0]-2+i,a[1]-2+j))
      elif a[0]-2+i>=0 and a[0]-2+i<H and a[1]-2+j>=0 and a[1]-2+j<W and (S[a[0]-2+i][a[1]-2+j]==-1 or S[a[0]-2+i][a[1]-2+j]>S[a[0]][a[1]]+1):
        S[a[0]-2+i][a[1]-2+j]=S[a[0]][a[1]]+1
        dq.append((a[0]-2+i,a[1]-2+j))

print(S[Dh][Dw])

Fixed submission:
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

S=[]
for i in range(H):
  s=list(input())
  S.append([10**10 if i =="." else -1 for i in s])
visit=[[False for i in range(W)] for j in range(H)]

dq = deque()
dq.append((Ch,Cw,0))
S[Ch][Cw]=0
counter=0

while dq:
  a=dq.popleft()
  if visit[a[0]][a[1]]==True:
    continue
  elif S[a[0]][a[1]]==counter:
    visit[a[0]][a[1]]=True
  elif a[2]==counter+1:
    visit[a[0]][a[1]]=True
    counter+=1
  for i in range(5):
    for j in range(5):
      if a[0]-2+i>=0 and a[0]-2+i<H and a[1]-2+j>=0 and a[1]-2+j<W:
        if abs(i-2)+abs(j-2)==1 and S[a[0]][a[1]]<S[a[0]-2+i][a[1]-2+j] and visit[a[0]-2+i][a[1]-2+j]==False:
          S[a[0]-2+i][a[1]-2+j]=counter
          dq.appendleft((a[0]-2+i,a[1]-2+j,counter))
        elif S[a[0]][a[1]]+1<S[a[0]-2+i][a[1]-2+j] and visit[a[0]-2+i][a[1]-2+j]==False:
          S[a[0]-2+i][a[1]-2+j]=counter+1
          dq.append((a[0]-2+i,a[1]-2+j,counter+1))
  #print(visit,counter,a,dq,"\n")
if S[Dh][Dw]==10**10:
  print(-1)
else:
  print(S[Dh][Dw])

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

S=[]
for i in range(H):
  s=list(input())
  S.append([-1 if i =="." else i for i in s])

dq = deque()
dq.append((Ch,Cw))
S[Ch][Cw]=0

while dq:
  a=dq.pop()
  for i in range(5):
    for j in range(5):
      if a[0]-2+i>=0 and a[0]-2+i<H and a[1]-2+j>=0 and a[1]-2+j<W and abs(i-2)+abs(j-2)==1 and (S[a[0]-2+i][a[1]-2+j]==-1 or (S[a[0]-2+i][a[1]-2+j]!="#" and S[a[0]-2+i][a[1]-2+j]>S[a[0]][a[1]])):
        S[a[0]-2+i][a[1]-2+j]=S[a[0]][a[1]]
        dq.appendleft((a[0]-2+i,a[1]-2+j))
      elif a[0]-2+i>=0 and a[0]-2+i<H and a[1]-2+j>=0 and a[1]-2+j<W and (S[a[0]-2+i][a[1]-2+j]==-1 or (S[a[0]-2+i][a[1]-2+j]!="#" and S[a[0]-2+i][a[1]-2+j]>S[a[0]][a[1]]+1)):
        S[a[0]-2+i][a[1]-2+j]=S[a[0]][a[1]]+1
        dq.append((a[0]-2+i,a[1]-2+j))

print(S[Dh][Dw])

Fixed submission:
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

S=[]
for i in range(H):
  s=list(input())
  S.append([10**10 if i =="." else -1 for i in s])
visit=[[False for i in range(W)] for j in range(H)]

dq = deque()
dq.append((Ch,Cw,0))
S[Ch][Cw]=0
counter=0

while dq:
  a=dq.popleft()
  if visit[a[0]][a[1]]==True:
    continue
  elif S[a[0]][a[1]]==counter:
    visit[a[0]][a[1]]=True
  elif a[2]==counter+1:
    visit[a[0]][a[1]]=True
    counter+=1
  for i in range(5):
    for j in range(5):
      if a[0]-2+i>=0 and a[0]-2+i<H and a[1]-2+j>=0 and a[1]-2+j<W:
        if abs(i-2)+abs(j-2)==1 and S[a[0]][a[1]]<S[a[0]-2+i][a[1]-2+j] and visit[a[0]-2+i][a[1]-2+j]==False:
          S[a[0]-2+i][a[1]-2+j]=counter
          dq.appendleft((a[0]-2+i,a[1]-2+j,counter))
        elif S[a[0]][a[1]]+1<S[a[0]-2+i][a[1]-2+j] and visit[a[0]-2+i][a[1]-2+j]==False:
          S[a[0]-2+i][a[1]-2+j]=counter+1
          dq.append((a[0]-2+i,a[1]-2+j,counter+1))
  #print(visit,counter,a,dq,"\n")
if S[Dh][Dw]==10**10:
  print(-1)
else:
  print(S[Dh][Dw])

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

S=[]
for i in range(H):
  s=list(input())
  S.append([-1 if i =="." else i for i in s])

dq = deque()
dq.append((Ch,Cw))
S[Ch][Cw]=0

while dq:
  a=dq.pop()
  if a[0]-1>=0 and (S[a[0]-1][a[1]]==-1 or (S[a[0]-1][a[1]]!="#" and S[a[0]-1][a[1]]>S[a[0]][a[1]])):
    S[a[0]-1][a[1]]=S[a[0]][a[1]]
    dq.appendleft((a[0]-1,a[1]))
  if a[0]+1<H and (S[a[0]+1][a[1]]==-1 or (S[a[0]+1][a[1]]!="#" and S[a[0]+1][a[1]]>S[a[0]][a[1]])):
    S[a[0]+1][a[1]]=S[a[0]][a[1]]
    dq.appendleft((a[0]+1,a[1]))
  if a[1]-1>=0 and (S[a[0]][a[1]-1]==-1 or (S[a[0]][a[1]-1]!="#" and S[a[0]][a[1]-1]>S[a[0]][a[1]])):
    S[a[0]][a[1]-1]=S[a[0]][a[1]]
    dq.appendleft((a[0],a[1]-1))
  if a[1]+1<W and (S[a[0]][a[1]+1]==-1 or (S[a[0]][a[1]+1]!="#" and S[a[0]][a[1]+1]>S[a[0]][a[1]])):
    S[a[0]][a[1]+1]=S[a[0]][a[1]]
    dq.appendleft((a[0],a[1]+1))
  for i in range(5):
    for j in range(5):
      if a[0]-2+i>=0 and a[0]-2+i<H and a[1]-2+j>=0 and a[1]-2+j<W and (S[a[0]-2+i][a[1]-2+j]==-1 or (S[a[0]-2+i][a[1]-2+j]!="#" and S[a[0]-2+i][a[1]-2+j]>=S[a[0]][a[1]]+1)):
        S[a[0]-2+i][a[1]-2+j]=S[a[0]][a[1]]+1
        dq.append((a[0]-2+i,a[1]-2+j))

print(S[Dh][Dw])

Fixed submission:
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

S=[]
for i in range(H):
  s=list(input())
  S.append([10**10 if i =="." else -1 for i in s])
visit=[[False for i in range(W)] for j in range(H)]

dq = deque()
dq.append((Ch,Cw,0))
S[Ch][Cw]=0
counter=0

while dq:
  a=dq.popleft()
  if visit[a[0]][a[1]]==True:
    continue
  elif S[a[0]][a[1]]==counter:
    visit[a[0]][a[1]]=True
  elif a[2]==counter+1:
    visit[a[0]][a[1]]=True
    counter+=1
  for i in range(5):
    for j in range(5):
      if a[0]-2+i>=0 and a[0]-2+i<H and a[1]-2+j>=0 and a[1]-2+j<W:
        if abs(i-2)+abs(j-2)==1 and S[a[0]][a[1]]<S[a[0]-2+i][a[1]-2+j] and visit[a[0]-2+i][a[1]-2+j]==False:
          S[a[0]-2+i][a[1]-2+j]=counter
          dq.appendleft((a[0]-2+i,a[1]-2+j,counter))
        elif S[a[0]][a[1]]+1<S[a[0]-2+i][a[1]-2+j] and visit[a[0]-2+i][a[1]-2+j]==False:
          S[a[0]-2+i][a[1]-2+j]=counter+1
          dq.append((a[0]-2+i,a[1]-2+j,counter+1))
  #print(visit,counter,a,dq,"\n")
if S[Dh][Dw]==10**10:
  print(-1)
else:
  print(S[Dh][Dw])

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

S=[]
for i in range(H):
  s=list(input())
  S.append([-1 if i =="." else i for i in s])

dq = deque()
dq.append((Ch,Cw))
S[Ch][Cw]=0

while dq:
  a=dq.pop()
  if a[0]-1>=0 and (S[a[0]-1][a[1]]==-1 or (S[a[0]-1][a[1]]!="#" and S[a[0]-1][a[1]]>S[a[0]][a[1]])):
    S[a[0]-1][a[1]]=S[a[0]][a[1]]
    dq.appendleft((a[0]-1,a[1]))
  if a[0]+1<H and (S[a[0]+1][a[1]]==-1 or (S[a[0]+1][a[1]]!="#" and S[a[0]+1][a[1]]>S[a[0]][a[1]])):
    S[a[0]+1][a[1]]=S[a[0]][a[1]]
    dq.appendleft((a[0]+1,a[1]))
  if a[1]-1>=0 and (S[a[0]][a[1]-1]==-1 or (S[a[0]][a[1]-1]!="#" and S[a[0]][a[1]-1]>S[a[0]][a[1]])):
    S[a[0]][a[1]-1]=S[a[0]][a[1]]
    dq.appendleft((a[0],a[1]-1))
  if a[1]+1<W and (S[a[0]][a[1]+1]==-1 or (S[a[0]][a[1]+1]!="#" and S[a[0]][a[1]+1]>S[a[0]][a[1]])):
    S[a[0]][a[1]+1]=S[a[0]][a[1]]
    dq.appendleft((a[0],a[1]+1))
  for i in range(5):
    for j in range(5):
      if a[0]-2+i>=0 and a[0]-2+i<H and a[1]-2+j>=0 and a[1]-2+j<W and (S[a[0]-2+i][a[1]-2+j]==-1 or S[a[0]-2+i][a[1]-2+j]>=S[a[0]][a[1]]+1):
        S[a[0]-2+i][a[1]-2+j]=S[a[0]][a[1]]+1
        dq.append((a[0]-2+i,a[1]-2+j))

print(S[Dh][Dw])

Fixed submission:
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

S=[]
for i in range(H):
  s=list(input())
  S.append([10**10 if i =="." else -1 for i in s])
visit=[[False for i in range(W)] for j in range(H)]

dq = deque()
dq.append((Ch,Cw,0))
S[Ch][Cw]=0
counter=0

while dq:
  a=dq.popleft()
  if visit[a[0]][a[1]]==True:
    continue
  elif S[a[0]][a[1]]==counter:
    visit[a[0]][a[1]]=True
  elif a[2]==counter+1:
    visit[a[0]][a[1]]=True
    counter+=1
  for i in range(5):
    for j in range(5):
      if a[0]-2+i>=0 and a[0]-2+i<H and a[1]-2+j>=0 and a[1]-2+j<W:
        if abs(i-2)+abs(j-2)==1 and S[a[0]][a[1]]<S[a[0]-2+i][a[1]-2+j] and visit[a[0]-2+i][a[1]-2+j]==False:
          S[a[0]-2+i][a[1]-2+j]=counter
          dq.appendleft((a[0]-2+i,a[1]-2+j,counter))
        elif S[a[0]][a[1]]+1<S[a[0]-2+i][a[1]-2+j] and visit[a[0]-2+i][a[1]-2+j]==False:
          S[a[0]-2+i][a[1]-2+j]=counter+1
          dq.append((a[0]-2+i,a[1]-2+j,counter+1))
  #print(visit,counter,a,dq,"\n")
if S[Dh][Dw]==10**10:
  print(-1)
else:
  print(S[Dh][Dw])