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, Cw, Dh, Dw = Ch - 1, Cw - 1, Dh - 1, Dw - 1
maze = [list(input()) for i in range(H)]
#print(maze)
  
ans = [[-1] * W for i in range(H)]  
ans[Ch][Cw] = 0
q = deque([[0, Ch, Cw]])  
one = [[0, 1], [0, -1], [1, 0], [-1, 0]]
two = [[2, 2], [2, 1], [2, 0], [2, -1], [2, -2], [1, 2], [1, 1], [1, -1], [1, -2], [0, 2], [0, -2], [-1, 2], [-1, 1], [-1, -1], [-1, -2], [-2, 2], [-2, 1], [-2, 0], [-2, -1], [-2, -2]] 
while q:
  cnt, h, w = q.popleft()
  if ans[h][w] < cnt:
    continue
  for i, j in one:
    if (0 <= h + i < H) and (0 <= w + j < W) and (maze[h + i][w + j] != "#"):
        if ans[h + i][w + j] == -1 or ans[h + i][w + j] > cnt:
          ans[h + i][w + j] = cnt
          q.appendleft([cnt, h + i, w + j])
  for i, j in two:  
    if (0 <= h + i < H) and (0 <= w + j < W) and (maze[h + i][w + j] != "#"):
        if ans[h + i][w + j] == -1 or ans[h + i][w + j] > cnt + 1:
          ans[h + i][w + j] = cnt + 1
          q.appendleft([cnt + 1, h + i, w + j])
              
print(ans[Dh][Dw])              
          
              
          
          
    
    
    

  


Fixed submission:

H, W = map(int, input().split())
Ch, Cw = map(int, input().split())
Dh, Dw = map(int, input().split())
Ch, Cw, Dh, Dw = Ch - 1, Cw - 1, Dh - 1, Dw - 1
maze = [list(input()) for i in range(H)]
#print(maze)
  
ans = [[-1] * W for i in range(H)]  
ans[Ch][Cw] = 0
from collections import deque
q = deque([[0, Ch, Cw]])  
one = [[0, 1], [0, -1], [1, 0], [-1, 0]]
two = [[2, 2], [2, 1], [2, 0], [2, -1], [2, -2], [1, 2], [1, 1], [1, -1], [1, -2], [0, 2], [0, -2], [-1, 2], [-1, 1], [-1, -1], [-1, -2], [-2, 2], [-2, 1], [-2, 0], [-2, -1], [-2, -2]] 
while q:
  cnt, h, w = q.popleft()
  if ans[h][w] < cnt:
    continue
  for i, j in one:
    if (0 <= h + i < H) and (0 <= w + j < W) and (maze[h + i][w + j] != "#"):
        if ans[h + i][w + j] == -1 or ans[h + i][w + j] > cnt:
          ans[h + i][w + j] = cnt
          q.appendleft([cnt, h + i, w + j])
  for i, j in two:  
    if (0 <= h + i < H) and (0 <= w + j < W) and (maze[h + i][w + j] != "#"):
        if ans[h + i][w + j] == -1 or ans[h + i][w + j] > cnt + 1:
          ans[h + i][w + j] = cnt + 1
          q.append([cnt + 1, h + i, w + j])
              
print(ans[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, Cw, Dh, Dw = Ch - 1, Cw - 1, Dh - 1, Dw - 1
maze = [list(input()) for i in range(H)]
#print(maze)
  
ans = [[-1] * W for i in range(H)]  
ans[Ch][Cw] = 0
q = deque([[0, Ch, Cw]])  
one = [[0, 1], [0, -1], [1, 0], [-1, 0]]
two = [[2, 2], [2, 1], [2, 0], [2, -1], [2, -2], [1, 2], [1, 1], [1, -1], [1, -2], [0, -2], [0, 2], [-1, 2], [-1, -1], [-1, 1], [-1, 2], [-2, 2], [-2, 1], [-2, 0], [-2, -1], [-2, -2]] 
while q:
  cnt, h, w = q.popleft()
  if ans[h][w] < cnt:
    continue
  for i, j in one:
    if (0 <= h + i < H) and (0 <= w + j < W) and (maze[h + i][w + j] != "#"):
        if ans[h + i][w + j] == -1 or ans[h + i][w + j] > cnt:
          ans[h + i][w + j] = cnt
          q.appendleft([cnt, h + i, w + j])
  for i, j in two:  
    if (0 <= h + i < H) and (0 <= w + j < W) and (maze[h + i][w + j] != "#"):
        if ans[h + i][w + j] == -1 or ans[h + i][w + j] > cnt + 1:
          ans[h + i][w + j] = cnt + 1
          q.appendleft([cnt + 1, h + i, w + j])
              
print(ans[Dh][Dw])              
          
              
          
          
    
    
    

  


Fixed submission:

H, W = map(int, input().split())
Ch, Cw = map(int, input().split())
Dh, Dw = map(int, input().split())
Ch, Cw, Dh, Dw = Ch - 1, Cw - 1, Dh - 1, Dw - 1
maze = [list(input()) for i in range(H)]
#print(maze)
  
ans = [[-1] * W for i in range(H)]  
ans[Ch][Cw] = 0
from collections import deque
q = deque([[0, Ch, Cw]])  
one = [[0, 1], [0, -1], [1, 0], [-1, 0]]
two = [[2, 2], [2, 1], [2, 0], [2, -1], [2, -2], [1, 2], [1, 1], [1, -1], [1, -2], [0, 2], [0, -2], [-1, 2], [-1, 1], [-1, -1], [-1, -2], [-2, 2], [-2, 1], [-2, 0], [-2, -1], [-2, -2]] 
while q:
  cnt, h, w = q.popleft()
  if ans[h][w] < cnt:
    continue
  for i, j in one:
    if (0 <= h + i < H) and (0 <= w + j < W) and (maze[h + i][w + j] != "#"):
        if ans[h + i][w + j] == -1 or ans[h + i][w + j] > cnt:
          ans[h + i][w + j] = cnt
          q.appendleft([cnt, h + i, w + j])
  for i, j in two:  
    if (0 <= h + i < H) and (0 <= w + j < W) and (maze[h + i][w + j] != "#"):
        if ans[h + i][w + j] == -1 or ans[h + i][w + j] > cnt + 1:
          ans[h + i][w + j] = cnt + 1
          q.append([cnt + 1, h + i, w + j])
              
print(ans[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, Cw, Dh, Dw = Ch - 1, Cw - 1, Dh - 1, Dw - 1
maze = [0] * H
for i in range(H):
  maze[i] = str(input())
  
ans = [[-1] * W for i in range(H)]  
ans[Ch][Cw] = 0
q = deque([[0, Ch, Cw]])  
while q:
  cnt, h, w = q.popleft()
  if ans[h][w] < cnt:
    continue
  for i in [-2, -1, 0, 1, 2]:
    for j in [-2, -1, 0, 1, 2]:
      if (0 <= h + i < H) and (0 <= w + j < W):
        if i== 0 and j == 0:
          continue
        elif abs(i) + abs(j) == 1:
          if maze[h + i][w + j] == ".":
            if ans[h + i][w + j] == -1 or ans[h + i][w + j] > cnt:
              ans[h + i][w + j] = cnt
              q.appendleft([cnt, h + i, w + j])
        else:
          if maze[h + i][w + j] == ".":
            if ans[h + i][w + j] == -1 or ans[h + i][w + j] > cnt + 1:
              ans[h + i][w + j] = cnt + 1
              q.appendleft([cnt + 1, h + i, w + j])
              
print(ans[Dh][Dw])              
          
              
          
          
    
    
    

  


Fixed submission:

H, W = map(int, input().split())
Ch, Cw = map(int, input().split())
Dh, Dw = map(int, input().split())
Ch, Cw, Dh, Dw = Ch - 1, Cw - 1, Dh - 1, Dw - 1
maze = [list(input()) for i in range(H)]
#print(maze)
  
ans = [[-1] * W for i in range(H)]  
ans[Ch][Cw] = 0
from collections import deque
q = deque([[0, Ch, Cw]])  
one = [[0, 1], [0, -1], [1, 0], [-1, 0]]
two = [[2, 2], [2, 1], [2, 0], [2, -1], [2, -2], [1, 2], [1, 1], [1, -1], [1, -2], [0, 2], [0, -2], [-1, 2], [-1, 1], [-1, -1], [-1, -2], [-2, 2], [-2, 1], [-2, 0], [-2, -1], [-2, -2]] 
while q:
  cnt, h, w = q.popleft()
  if ans[h][w] < cnt:
    continue
  for i, j in one:
    if (0 <= h + i < H) and (0 <= w + j < W) and (maze[h + i][w + j] != "#"):
        if ans[h + i][w + j] == -1 or ans[h + i][w + j] > cnt:
          ans[h + i][w + j] = cnt
          q.appendleft([cnt, h + i, w + j])
  for i, j in two:  
    if (0 <= h + i < H) and (0 <= w + j < W) and (maze[h + i][w + j] != "#"):
        if ans[h + i][w + j] == -1 or ans[h + i][w + j] > cnt + 1:
          ans[h + i][w + j] = cnt + 1
          q.append([cnt + 1, h + i, w + j])
              
print(ans[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, Cw, Dh, Dw = Ch - 1, Cw - 1, Dh - 1, Dw - 1
maze = [0] * H
for i in range(H):
  maze[i] = str(input())
  
ans = [[-1] * W for i in range(H)]  
ans[Ch][Cw] = 0
q = deque([[0, Ch, Cw]])  
while q:
  cnt, h, w = q.popleft()
  if ans[h][w] < cnt:
    continue
  for i in [-2, -1, 0, 1, 2]:
    for j in [-2, -1, 0, 1, 2]:
      if (0 <= h + i < H) and (0 <= w + j < W):
        if i== 0 and j == 0:
          continue
        elif abs(i) + abs(j) == 1:
          if maze[h + i][w + j] == ".":
            if ans[h + i][w + j] == -1 or ans[h + i][w + j] > cnt:
              ans[h + i][w + j] = cnt
              q.appendleft([cnt, h + i, w + j])
        else:
          if maze[h + i][w + j] == ".":
            if ans[h + i][w + j] == -1 or ans[h + i][w + j] > cnt + 1:
              ans[h + i][w + j] = cnt + 1
              q.appendleft([cnt + 1, h + i, w + j])
              
print(ans[Dh][Dw])              
          
              
          
          
    
    
    

  


Fixed submission:

H, W = map(int, input().split())
Ch, Cw = map(int, input().split())
Dh, Dw = map(int, input().split())
Ch, Cw, Dh, Dw = Ch - 1, Cw - 1, Dh - 1, Dw - 1
maze = [list(input()) for i in range(H)]
#print(maze)
  
ans = [[-1] * W for i in range(H)]  
ans[Ch][Cw] = 0
from collections import deque
q = deque([[0, Ch, Cw]])  
one = [[0, 1], [0, -1], [1, 0], [-1, 0]]
two = [[2, 2], [2, 1], [2, 0], [2, -1], [2, -2], [1, 2], [1, 1], [1, -1], [1, -2], [0, 2], [0, -2], [-1, 2], [-1, 1], [-1, -1], [-1, -2], [-2, 2], [-2, 1], [-2, 0], [-2, -1], [-2, -2]] 
while q:
  cnt, h, w = q.popleft()
  if ans[h][w] < cnt:
    continue
  for i, j in one:
    if (0 <= h + i < H) and (0 <= w + j < W) and (maze[h + i][w + j] != "#"):
        if ans[h + i][w + j] == -1 or ans[h + i][w + j] > cnt:
          ans[h + i][w + j] = cnt
          q.appendleft([cnt, h + i, w + j])
  for i, j in two:  
    if (0 <= h + i < H) and (0 <= w + j < W) and (maze[h + i][w + j] != "#"):
        if ans[h + i][w + j] == -1 or ans[h + i][w + j] > cnt + 1:
          ans[h + i][w + j] = cnt + 1
          q.append([cnt + 1, h + i, w + j])
              
print(ans[Dh][Dw])