Buggy python submission (verdict: Time Limit Exceeded):
#入力
h,w=map(int,input().split())
ch,cw=map(int,input().split())
dh,dw=map(int,input().split())
s=[input() for i in range(h)]

#for i in range(h):
#  s_=list(input())
#  s.append(s_)
#幅優先探索
from collections import deque
q=deque([(ch-1,cw-1)])
used=[[float("INF")]*w for i in range(h)]
used[ch-1][cw-1]=0
X=((-1,0),(1,0),(0,1),(0,-1))
Y=((-2,-2),(-2,-1),(-2,0),(-2,1),(-2,2),(-1,-2),(-1,-1),(-1,1),(-1,2),(0,-2),(0,1),(0,2),(1,-2),(1,-1),(1,1),(1,2),(2,-2),(2,-1),(2,0),(2,1),(2,2))
while len(q)>0:
  y,x=q.popleft()
  for dy,dx in X:
    nx=x+dx
    ny=y+dy
    if nx>=0 and nx<w and ny>=0 and ny<h and s[ny][nx]==".":
      if used[ny][nx]>used[y][x]:
        used[ny][nx]=used[y][x]
        q.appendleft((ny,nx))
  for dy,dx in Y:
    nx=x+dx
    ny=y+dy
    if nx>=0 and nx<w and ny>=0 and ny<h and s[ny][nx]==".":
      if used[ny][nx]>used[y][x]:
        used[ny][nx]=used[y][x]+1
        q.append((ny,nx))

if used[dh-1][dw-1]==float("INF"):
  print(-1)
else:
  print(used[dh-1][dw-1])

      
      
      
    
  
  


Fixed submission:
#入力
h,w=map(int,input().split())
ch,cw=map(int,input().split())
dh,dw=map(int,input().split())
from sys import stdin
s=[stdin.readline() for i in range(h)]

#for i in range(h):
#  s_=list(input())
#  s.append(s_)
#幅優先探索
from collections import deque
q=deque([(ch-1,cw-1)])
used=[[float("INF")]*w for i in range(h)]
used[ch-1][cw-1]=0
X=((-1,0),(1,0),(0,1),(0,-1))
Y=((-2,-2),(-2,-1),(-2,0),(-2,1),(-2,2),(-1,-2),(-1,-1),(-1,1),(-1,2),(0,-2),(0,1),(0,2),(1,-2),(1,-1),(1,1),(1,2),(2,-2),(2,-1),(2,0),(2,1),(2,2))
while len(q)>0:
  y,x=q.popleft()
  for dy,dx in X:
    nx=x+dx
    ny=y+dy
    if nx>=0 and nx<w and ny>=0 and ny<h and s[ny][nx]==".":
      if used[ny][nx]>used[y][x]:
        used[ny][nx]=used[y][x]
        q.appendleft((ny,nx))
  for dy,dx in Y:
    nx=x+dx
    ny=y+dy
    if nx>=0 and nx<w and ny>=0 and ny<h and s[ny][nx]==".":
      if used[ny][nx]>used[y][x]:
        used[ny][nx]=used[y][x]+1
        q.append((ny,nx))

if used[dh-1][dw-1]==float("INF"):
  print(-1)
else:
  print(used[dh-1][dw-1])

Buggy python submission (verdict: Time Limit Exceeded):
#入力
h,w=map(int,input().split())
ch,cw=map(int,input().split())
dh,dw=map(int,input().split())
s=[]
for i in range(h):
  s_=list(input())
  s.append(s_)
#幅優先探索
from collections import deque
q=deque([(ch-1,cw-1)])
used=[[float("INF")]*w for i in range(h)]
used[ch-1][cw-1]=0
X=((-1,0),(1,0),(0,1),(0,-1))
Y=((-2,-2),(-2,-1),(-2,0),(-2,1),(-2,2),(-1,-2),(-1,-1),(-1,1),(-1,2),(0,-2),(0,1),(0,2),(1,-2),(1,-1),(1,1),(1,2),(2,-2),(2,-1),(2,0),(2,1),(2,2))
while len(q)>0:
  y,x=q.popleft()
  for dy,dx in X:
    nx=x+dx
    ny=y+dy
    if nx>=0 and nx<w and ny>=0 and ny<h and s[ny][nx]==".":
      if used[ny][nx]>used[y][x]:
        used[ny][nx]=used[y][x]
        q.appendleft((ny,nx))
  for dy,dx in Y:
    nx=x+dx
    ny=y+dy
    if nx>=0 and nx<w and ny>=0 and ny<h and s[ny][nx]==".":
      if used[ny][nx]>used[y][x]:
        used[ny][nx]=used[y][x]+1
        q.append((ny,nx))

if used[dh-1][dw-1]==float("INF"):
  print(-1)
else:
  print(used[dh-1][dw-1])

      
      
      
    
  
  


Fixed submission:
#入力
h,w=map(int,input().split())
ch,cw=map(int,input().split())
dh,dw=map(int,input().split())
from sys import stdin
s=[stdin.readline() for i in range(h)]

#for i in range(h):
#  s_=list(input())
#  s.append(s_)
#幅優先探索
from collections import deque
q=deque([(ch-1,cw-1)])
used=[[float("INF")]*w for i in range(h)]
used[ch-1][cw-1]=0
X=((-1,0),(1,0),(0,1),(0,-1))
Y=((-2,-2),(-2,-1),(-2,0),(-2,1),(-2,2),(-1,-2),(-1,-1),(-1,1),(-1,2),(0,-2),(0,1),(0,2),(1,-2),(1,-1),(1,1),(1,2),(2,-2),(2,-1),(2,0),(2,1),(2,2))
while len(q)>0:
  y,x=q.popleft()
  for dy,dx in X:
    nx=x+dx
    ny=y+dy
    if nx>=0 and nx<w and ny>=0 and ny<h and s[ny][nx]==".":
      if used[ny][nx]>used[y][x]:
        used[ny][nx]=used[y][x]
        q.appendleft((ny,nx))
  for dy,dx in Y:
    nx=x+dx
    ny=y+dy
    if nx>=0 and nx<w and ny>=0 and ny<h and s[ny][nx]==".":
      if used[ny][nx]>used[y][x]:
        used[ny][nx]=used[y][x]+1
        q.append((ny,nx))

if used[dh-1][dw-1]==float("INF"):
  print(-1)
else:
  print(used[dh-1][dw-1])

Buggy python submission (verdict: Time Limit Exceeded):
#入力
h,w=map(int,input().split())
ch,cw=map(int,input().split())
dh,dw=map(int,input().split())
s=[]
for i in range(h):
  s_=list(input())
  s.append(s_)
#幅優先探索
from collections import deque
q=deque([(ch-1,cw-1)])
used=[[float("INF")]*w for i in range(h)]
used[ch-1][cw-1]=0
while len(q)>0:
  y,x=q.popleft()
  X=((-1,0),(1,0),(0,1),(0,-1))
  for dy,dx in X:
    nx=x+dx
    ny=y+dy
    if nx>=0 and nx<w and ny>=0 and ny<h and s[ny][nx]==".":
      if used[ny][nx]>used[y][x]:
        used[ny][nx]=used[y][x]
        q.appendleft((ny,nx))
  Y=(-2,-1,0,1,2)
  for dx in Y:
    for dy in Y:
      if not(dx==0 and dy==0):
        if (dy,dx) not in X:
          nx=x+dx
          ny=y+dy
          if nx>=0 and nx<w and ny>=0 and ny<h and s[ny][nx]==".":
            if used[ny][nx]>used[y][x]:
              used[ny][nx]=used[y][x]+1
              q.append((ny,nx))

if used[dh-1][dw-1]==float("INF"):
  print(-1)
else:
  print(used[dh-1][dw-1])

      
      
      
    
  
  


Fixed submission:
#入力
h,w=map(int,input().split())
ch,cw=map(int,input().split())
dh,dw=map(int,input().split())
from sys import stdin
s=[stdin.readline() for i in range(h)]

#for i in range(h):
#  s_=list(input())
#  s.append(s_)
#幅優先探索
from collections import deque
q=deque([(ch-1,cw-1)])
used=[[float("INF")]*w for i in range(h)]
used[ch-1][cw-1]=0
X=((-1,0),(1,0),(0,1),(0,-1))
Y=((-2,-2),(-2,-1),(-2,0),(-2,1),(-2,2),(-1,-2),(-1,-1),(-1,1),(-1,2),(0,-2),(0,1),(0,2),(1,-2),(1,-1),(1,1),(1,2),(2,-2),(2,-1),(2,0),(2,1),(2,2))
while len(q)>0:
  y,x=q.popleft()
  for dy,dx in X:
    nx=x+dx
    ny=y+dy
    if nx>=0 and nx<w and ny>=0 and ny<h and s[ny][nx]==".":
      if used[ny][nx]>used[y][x]:
        used[ny][nx]=used[y][x]
        q.appendleft((ny,nx))
  for dy,dx in Y:
    nx=x+dx
    ny=y+dy
    if nx>=0 and nx<w and ny>=0 and ny<h and s[ny][nx]==".":
      if used[ny][nx]>used[y][x]:
        used[ny][nx]=used[y][x]+1
        q.append((ny,nx))

if used[dh-1][dw-1]==float("INF"):
  print(-1)
else:
  print(used[dh-1][dw-1])

Buggy python submission (verdict: Time Limit Exceeded):
#入力
h,w=map(int,input().split())
ch,cw=map(int,input().split())
dh,dw=map(int,input().split())
s=[]
for i in range(h):
  s_=list(input())
  s.append(s_)
#幅優先探索
from collections import deque
q=deque([(ch-1,cw-1)])
used=[[float("INF")]*w for i in range(h)]
used[ch-1][cw-1]=0
while len(q)>0:
  y,x=q.popleft()
  X=((-1,0),(1,0),(0,1),(0,-1))
  for dy,dx in X:
    nx=x+dx
    ny=y+dy
    if nx>=0 and nx<w and ny>=0 and ny<h and s[ny][nx]==".":
      if used[ny][nx]>used[y][x]:
        used[ny][nx]=used[y][x]
        q.appendleft((ny,nx))
  Y=(-2,-1,0,1,2)
  for dx in Y:
    for dy in Y:
      if not(dx==0 and dy==0):
        if (dy,dx) not in X:
          nx=x+dx
          ny=y+dy
          if nx>=0 and nx<w and ny>=0 and ny<h and s[ny][nx]==".":
            if used[ny][nx]>used[y][x]:
              used[ny][nx]=used[y][x]+1
              q.append((ny,nx))

if used[dh-1][dw-1]==float("INF"):
  print(-1)
else:
  print(used[dh-1][dw-1])

      
      
      
    
  
  


Fixed submission:
#入力
h,w=map(int,input().split())
ch,cw=map(int,input().split())
dh,dw=map(int,input().split())
from sys import stdin
s=[stdin.readline() for i in range(h)]

#for i in range(h):
#  s_=list(input())
#  s.append(s_)
#幅優先探索
from collections import deque
q=deque([(ch-1,cw-1)])
used=[[float("INF")]*w for i in range(h)]
used[ch-1][cw-1]=0
X=((-1,0),(1,0),(0,1),(0,-1))
Y=((-2,-2),(-2,-1),(-2,0),(-2,1),(-2,2),(-1,-2),(-1,-1),(-1,1),(-1,2),(0,-2),(0,1),(0,2),(1,-2),(1,-1),(1,1),(1,2),(2,-2),(2,-1),(2,0),(2,1),(2,2))
while len(q)>0:
  y,x=q.popleft()
  for dy,dx in X:
    nx=x+dx
    ny=y+dy
    if nx>=0 and nx<w and ny>=0 and ny<h and s[ny][nx]==".":
      if used[ny][nx]>used[y][x]:
        used[ny][nx]=used[y][x]
        q.appendleft((ny,nx))
  for dy,dx in Y:
    nx=x+dx
    ny=y+dy
    if nx>=0 and nx<w and ny>=0 and ny<h and s[ny][nx]==".":
      if used[ny][nx]>used[y][x]:
        used[ny][nx]=used[y][x]+1
        q.append((ny,nx))

if used[dh-1][dw-1]==float("INF"):
  print(-1)
else:
  print(used[dh-1][dw-1])

Buggy python submission (verdict: Time Limit Exceeded):
#入力
h,w=map(int,input().split())
ch,cw=map(int,input().split())
dh,dw=map(int,input().split())
s=[]
for i in range(h):
  s_=list(input())
  s.append(s_)
#幅優先探索
from collections import deque
q=deque([[ch-1,cw-1]])
used=[[float("INF")]*w for i in range(h)]
used[ch-1][cw-1]=0
while len(q)>0:
  y,x=q.popleft()
  X=[[-1,0],[1,0],[0,1],[0,-1]]
  for dy,dx in X:
    nx=x+dx
    ny=y+dy
    if nx>=0 and nx<w and ny>=0 and ny<h and s[ny][nx]==".":
      if used[ny][nx]>used[y][x]:
        used[ny][nx]=used[y][x]
        q.appendleft([ny,nx])
  Y=[-2,-1,0,1,2]
  for dx in Y:
    for dy in Y:
      if not(dx==0 and dy==0):
        if [dy,dx] not in X:
          nx=x+dx
          ny=y+dy
          if nx>=0 and nx<w and ny>=0 and ny<h and s[ny][nx]==".":
            if used[ny][nx]>used[y][x]:
              used[ny][nx]=used[y][x]+1
              q.append([ny,nx])

if used[dh-1][dw-1]==float("INF"):
  print(-1)
else:
  print(used[dh-1][dw-1])

      
      
      
    
  
  


Fixed submission:
#入力
h,w=map(int,input().split())
ch,cw=map(int,input().split())
dh,dw=map(int,input().split())
from sys import stdin
s=[stdin.readline() for i in range(h)]

#for i in range(h):
#  s_=list(input())
#  s.append(s_)
#幅優先探索
from collections import deque
q=deque([(ch-1,cw-1)])
used=[[float("INF")]*w for i in range(h)]
used[ch-1][cw-1]=0
X=((-1,0),(1,0),(0,1),(0,-1))
Y=((-2,-2),(-2,-1),(-2,0),(-2,1),(-2,2),(-1,-2),(-1,-1),(-1,1),(-1,2),(0,-2),(0,1),(0,2),(1,-2),(1,-1),(1,1),(1,2),(2,-2),(2,-1),(2,0),(2,1),(2,2))
while len(q)>0:
  y,x=q.popleft()
  for dy,dx in X:
    nx=x+dx
    ny=y+dy
    if nx>=0 and nx<w and ny>=0 and ny<h and s[ny][nx]==".":
      if used[ny][nx]>used[y][x]:
        used[ny][nx]=used[y][x]
        q.appendleft((ny,nx))
  for dy,dx in Y:
    nx=x+dx
    ny=y+dy
    if nx>=0 and nx<w and ny>=0 and ny<h and s[ny][nx]==".":
      if used[ny][nx]>used[y][x]:
        used[ny][nx]=used[y][x]+1
        q.append((ny,nx))

if used[dh-1][dw-1]==float("INF"):
  print(-1)
else:
  print(used[dh-1][dw-1])

Buggy python submission (verdict: Time Limit Exceeded):
#入力
h,w=map(int,input().split())
ch,cw=map(int,input().split())
dh,dw=map(int,input().split())
s=[]
for i in range(h):
  s_=list(input())
  s.append(s_)
#幅優先探索
from collections import deque
q=deque([[ch-1,cw-1]])
used=[[float("INF")]*w for i in range(h)]
used[ch-1][cw-1]=0
while len(q)>0:
  y,x=q.popleft()
  X=[[-1,0],[1,0],[0,1],[0,-1]]
  for dy,dx in X:
    nx=x+dx
    ny=y+dy
    if nx>=0 and nx<w and ny>=0 and ny<h and s[ny][nx]==".":
      if used[ny][nx]>used[y][x]:
        used[ny][nx]=used[y][x]
        q.appendleft([ny,nx])
  Y=[-2,-1,0,1,2]
  for dx in Y:
    for dy in Y:
      if not(dx==0 and dy==0):
        if [dy,dx] not in X:
          nx=x+dx
          ny=y+dy
          if nx>=0 and nx<w and ny>=0 and ny<h and s[ny][nx]==".":
            if used[ny][nx]>used[y][x]:
              used[ny][nx]=used[y][x]+1
              q.append([ny,nx])

if used[dh-1][dw-1]==float("INF"):
  print(-1)
else:
  print(used[dh-1][dw-1])

      
      
      
    
  
  


Fixed submission:
#入力
h,w=map(int,input().split())
ch,cw=map(int,input().split())
dh,dw=map(int,input().split())
from sys import stdin
s=[stdin.readline() for i in range(h)]

#for i in range(h):
#  s_=list(input())
#  s.append(s_)
#幅優先探索
from collections import deque
q=deque([(ch-1,cw-1)])
used=[[float("INF")]*w for i in range(h)]
used[ch-1][cw-1]=0
X=((-1,0),(1,0),(0,1),(0,-1))
Y=((-2,-2),(-2,-1),(-2,0),(-2,1),(-2,2),(-1,-2),(-1,-1),(-1,1),(-1,2),(0,-2),(0,1),(0,2),(1,-2),(1,-1),(1,1),(1,2),(2,-2),(2,-1),(2,0),(2,1),(2,2))
while len(q)>0:
  y,x=q.popleft()
  for dy,dx in X:
    nx=x+dx
    ny=y+dy
    if nx>=0 and nx<w and ny>=0 and ny<h and s[ny][nx]==".":
      if used[ny][nx]>used[y][x]:
        used[ny][nx]=used[y][x]
        q.appendleft((ny,nx))
  for dy,dx in Y:
    nx=x+dx
    ny=y+dy
    if nx>=0 and nx<w and ny>=0 and ny<h and s[ny][nx]==".":
      if used[ny][nx]>used[y][x]:
        used[ny][nx]=used[y][x]+1
        q.append((ny,nx))

if used[dh-1][dw-1]==float("INF"):
  print(-1)
else:
  print(used[dh-1][dw-1])