Buggy python submission (verdict: Time Limit Exceeded):
import sys
input = sys.stdin.readline
#import heapq
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 _ in range(H):
  S.append(list(input()))
  
dpat = ((-1,0),(1,0),(0,-1),(0,1))
mpat = []
for i in range(-2,3):
  for j in range(-2,3):
    if (i,j) in dpat:
      continue
    if i == j and j == 0:
      continue
    mpat.append((i,j))
                
#print(mpat)

#BFS
visited = [[False] * W for _ in range(H)]
willSearch = [[False] * W for _ in range(H)]
Q = deque()
QN = deque()
Q.append((0,Ch,Cw))
QN.append((0,Ch,Cw))
while Q:
  while Q:
    c,x,y = Q.popleft()
    if visited[x][y]:
      continue
    visited[x][y] = True
    QN.append((c,x,y))
    #print(c,x,y)
    if x == Dh and y == Dw:
      print(c)
      exit(0)
    for dx,dy in dpat:
      nx,ny = x+dx, y+dy
      if 0<=nx<H and 0<=ny<W:
        if S[nx][ny] == "#":
          continue
        if visited[nx][ny] or willSearch[nx][ny]:
          continue
        Q.append((c,nx,ny))
        QN.append((c,nx,ny))
        willSearch[nx][ny] = True
  while QN:
    c,x,y = QN.popleft()
    for dx,dy in mpat:
      nx,ny = x+dx, y+dy
      if 0<=nx<H and 0<=ny<W:
        if S[nx][ny] == "#":
          continue
        if visited[nx][ny] or willSearch[nx][ny]:
          continue
        Q.append((c+1,nx,ny))
        #print("m", c+1, nx,ny)
        #willSearch[nx][ny] = True
      
print(-1)


Fixed submission:
import sys
input = sys.stdin.readline
#import heapq
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 _ in range(H):
  S.append(list(input()))
  
dpat = ((-1,0),(1,0),(0,-1),(0,1))
mpat = []
for i in range(-2,3):
  for j in range(-2,3):
    if (i,j) in dpat:
      continue
    if i == j and j == 0:
      continue
    mpat.append((i,j))
                
#print(mpat)

#BFS
visited = [[False] * W for _ in range(H)]
willSearch = [[False] * W for _ in range(H)]
Q = deque()
QN = deque()
Q.append((0,Ch,Cw))
QN.append((0,Ch,Cw))
while Q:
  while Q:
    c,x,y = Q.popleft()
    if visited[x][y]:
      continue
    visited[x][y] = True
    QN.append((c,x,y))
    #print(c,x,y)
    if x == Dh and y == Dw:
      print(c)
      exit(0)
    for dx,dy in dpat:
      nx,ny = x+dx, y+dy
      if 0<=nx<H and 0<=ny<W:
        if S[nx][ny] == "#":
          continue
        if visited[nx][ny] or willSearch[nx][ny]:
          continue
        Q.append((c,nx,ny))
        QN.append((c,nx,ny))
        willSearch[nx][ny] = True
  while QN:
    c,x,y = QN.popleft()
    for dx,dy in mpat:
      nx,ny = x+dx, y+dy
      if 0<=nx<H and 0<=ny<W:
        if S[nx][ny] == "#":
          continue
        if visited[nx][ny] or willSearch[nx][ny]:
          continue
        Q.append((c+1,nx,ny))
        #print("m", c+1, nx,ny)
        #willSearch[nx][ny] = True
      
print(-1)

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

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 _ in range(H):
  S.append(list(input()))
  
dpat = ((-1,0),(1,0),(0,-1),(0,1))
mpat = []
for i in range(-2,3):
  for j in range(-2,3):
    if (i,j) in dpat:
      continue
    if i == j and j == 0:
      continue
    mpat.append((i,j))
                
#print(mpat)

#dij
seen = [[False] * W for _ in range(H)]
h = []
# count_of_magic,x,y
heapq.heappush(h, (0,Ch,Cw))
while h:
  c,x,y = heapq.heappop(h)
  if seen[x][y]:
    continue
  seen[x][y] = True
  #print(c,x,y)
  if x == Dh and y == Dw:
    print(c)
    exit(0)
  for dx,dy in dpat:
    nx,ny = x+dx, y+dy
    if 0<=nx<H and 0<=ny<W:
      if seen[nx][ny] or S[nx][ny] == "#":
        continue
      heapq.heappush(h, (c,nx,ny))
  for dx,dy in mpat:
    nx,ny = x+dx, y+dy
    if 0<=nx<H and 0<=ny<W:
      if seen[nx][ny] or S[nx][ny] == "#":
        continue
      heapq.heappush(h, (c+1,nx,ny))
      
print(-1)

Fixed submission:
import sys
input = sys.stdin.readline
#import heapq
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 _ in range(H):
  S.append(list(input()))
  
dpat = ((-1,0),(1,0),(0,-1),(0,1))
mpat = []
for i in range(-2,3):
  for j in range(-2,3):
    if (i,j) in dpat:
      continue
    if i == j and j == 0:
      continue
    mpat.append((i,j))
                
#print(mpat)

#BFS
visited = [[False] * W for _ in range(H)]
willSearch = [[False] * W for _ in range(H)]
Q = deque()
QN = deque()
Q.append((0,Ch,Cw))
QN.append((0,Ch,Cw))
while Q:
  while Q:
    c,x,y = Q.popleft()
    if visited[x][y]:
      continue
    visited[x][y] = True
    QN.append((c,x,y))
    #print(c,x,y)
    if x == Dh and y == Dw:
      print(c)
      exit(0)
    for dx,dy in dpat:
      nx,ny = x+dx, y+dy
      if 0<=nx<H and 0<=ny<W:
        if S[nx][ny] == "#":
          continue
        if visited[nx][ny] or willSearch[nx][ny]:
          continue
        Q.append((c,nx,ny))
        QN.append((c,nx,ny))
        willSearch[nx][ny] = True
  while QN:
    c,x,y = QN.popleft()
    for dx,dy in mpat:
      nx,ny = x+dx, y+dy
      if 0<=nx<H and 0<=ny<W:
        if S[nx][ny] == "#":
          continue
        if visited[nx][ny] or willSearch[nx][ny]:
          continue
        Q.append((c+1,nx,ny))
        #print("m", c+1, nx,ny)
        #willSearch[nx][ny] = True
      
print(-1)

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

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 _ in range(H):
  S.append(list(input()))
  
dpat = ((-1,0),(1,0),(0,-1),(0,1))
mpat = []
for i in range(-2,3):
  for j in range(-2,3):
    if (i,j) in dpat:
      continue
    if i == j and j == 0:
      continue
    mpat.append((i,j))
                
#print(mpat)

#dij
seen = [[False] * W for _ in range(H)]
h = []
# count_of_magic,x,y
heapq.heappush(h, (0,Ch,Cw))
while h:
  c,x,y = heapq.heappop(h)
  if seen[x][y]:
    continue
  seen[x][y] = True
  #print(c,x,y)
  if x == Dh and y == Dw:
    print(c)
    exit(0)
  for dx,dy in dpat:
    nx,ny = x+dx, y+dy
    if 0<=nx<H and 0<=ny<W:
      if seen[nx][ny] or S[nx][ny] == "#":
        continue
      heapq.heappush(h, (c,nx,ny))
  for dx,dy in mpat:
    nx,ny = x+dx, y+dy
    if 0<=nx<H and 0<=ny<W:
      if seen[nx][ny] or S[nx][ny] == "#":
        continue
      heapq.heappush(h, (c+1,nx,ny))
      
print(-1)

Fixed submission:
import sys
input = sys.stdin.readline
#import heapq
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 _ in range(H):
  S.append(list(input()))
  
dpat = ((-1,0),(1,0),(0,-1),(0,1))
mpat = []
for i in range(-2,3):
  for j in range(-2,3):
    if (i,j) in dpat:
      continue
    if i == j and j == 0:
      continue
    mpat.append((i,j))
                
#print(mpat)

#BFS
visited = [[False] * W for _ in range(H)]
willSearch = [[False] * W for _ in range(H)]
Q = deque()
QN = deque()
Q.append((0,Ch,Cw))
QN.append((0,Ch,Cw))
while Q:
  while Q:
    c,x,y = Q.popleft()
    if visited[x][y]:
      continue
    visited[x][y] = True
    QN.append((c,x,y))
    #print(c,x,y)
    if x == Dh and y == Dw:
      print(c)
      exit(0)
    for dx,dy in dpat:
      nx,ny = x+dx, y+dy
      if 0<=nx<H and 0<=ny<W:
        if S[nx][ny] == "#":
          continue
        if visited[nx][ny] or willSearch[nx][ny]:
          continue
        Q.append((c,nx,ny))
        QN.append((c,nx,ny))
        willSearch[nx][ny] = True
  while QN:
    c,x,y = QN.popleft()
    for dx,dy in mpat:
      nx,ny = x+dx, y+dy
      if 0<=nx<H and 0<=ny<W:
        if S[nx][ny] == "#":
          continue
        if visited[nx][ny] or willSearch[nx][ny]:
          continue
        Q.append((c+1,nx,ny))
        #print("m", c+1, nx,ny)
        #willSearch[nx][ny] = True
      
print(-1)