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

def f1(x,y,xa,ya):
    if reach[xa][ya] > reach[x][y]:
         if c[xa][ya] == ".":
            reach[xa][ya] = reach[x][y]
            r.append([xa,ya])
            q.append([xa,ya])

def f2(x,y,xa,ya):
    if 0 <= xa <= h+1 and 0 <= ya <= w+1:
    
        if reach[xa][ya] > reach[x][y] + 1:
            if c[xa][ya] == ".":
                reach[xa][ya] = reach[x][y] + 1
                q.append([xa,ya])

h,w = map(int,input().split())
cx, cy = map(int,input().split())
dx, dy = map(int,input().split())

c = [0]*(h+2)
for i in range(1,h+1):
    c[i] = [0] + list(input()) + [0]
c[0]  = [0]*(w+2)
c[-1] = [0]*(w+2)

reach = [[float("Inf") for j in range(w+2)] for i in range(h+2)]
q = deque([])

reach[cx][cy] = 0
q.append([cx,cy])

ans = 0

while q:

    
    
    x,y = q.popleft()
    
    r = deque()
    r.append([x,y])
    while r:
        xx,yy = r.popleft()
        
        f1(xx,yy,xx-1,yy)
        f1(xx,yy,xx+1,yy)
        f1(xx,yy,xx,yy-1)
        f1(xx,yy,xx,yy+1)
    
    for i in range(-2,3):
        for j in range(-2,3):
            f2(x,y,x+i,y+j)

if reach[dx][dy] == float("Inf"):
    print(-1)
else:
    print(reach[dx][dy])


Fixed submission:
from collections import deque
import time


def f1(x,y,xa,ya):
    if reach[xa][ya] == -1 or reach[xa][ya] > reach[x][y]:
         if c[xa][ya] == ".":
            reach[xa][ya] = reach[x][y]
            r.append([xa,ya])
            q.append([xa,ya])

            
            
def f2(x,y,xa,ya):
    if 0 <= xa <= h and 0 <= ya <= w:
    
        if reach[xa][ya] == -1 or reach[xa][ya] > reach[x][y] + 1:
            if c[xa][ya] == ".":
                reach[xa][ya] = reach[x][y] + 1
                q.append([xa,ya])

h,w = map(int,input().split())
cx, cy = map(int,input().split())
dx, dy = map(int,input().split())

t0 = time.time()

c = ["#"]*(h+2)
for i in range(1,h+1):
    c[i] = ["#"] + list(input()) + ["#"]
c[0]  = [0]*(w+2)
c[-1] = [0]*(w+2)

reach = [[-1 for j in range(w+2)] for i in range(h+2)]
q = deque([])

reach[cx][cy] = 0
q.append([cx,cy])

ans = 0

while q:
    
    if time.time() - t0 >= 1.5:
        break
    
    
    x,y = q.popleft()
    
    r = deque()
    r.append([x,y])
    while r:
        xx,yy = r.popleft()
        
        f1(xx,yy,xx-1,yy)
        f1(xx,yy,xx+1,yy)
        f1(xx,yy,xx,yy-1)
        f1(xx,yy,xx,yy+1)
    
    for i in range(-2,3):
        for j in range(-2,3):
            f2(x,y,x+i,y+j)


print(reach[dx][dy])

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

def f1(x,y,xa,ya):
    if reach[xa][ya] == -1 or reach[xa][ya] > reach[x][y]:
         if c[xa][ya] == ".":
            reach[xa][ya] = reach[x][y]
            r.append([xa,ya])
            q.append([xa,ya])

def f2(x,y,xa,ya):
    if 0 <= xa <= h+1 and 0 <= ya <= w+1:
    
        if reach[xa][ya] == -1 or reach[xa][ya] > reach[x][y] + 1:
            if c[xa][ya] == ".":
                reach[xa][ya] = reach[x][y] + 1
                q.append([xa,ya])

h,w = map(int,input().split())
cx, cy = map(int,input().split())
dx, dy = map(int,input().split())

c = [0]*(h+2)
for i in range(1,h+1):
    c[i] = [0] + list(input()) + [0]
c[0]  = [0]*(w+2)
c[-1] = [0]*(w+2)

reach = [[-1 for j in range(w+2)] for i in range(h+2)]
q = deque([])

reach[cx][cy] = 0
q.append([cx,cy])

ans = 0

while q:

    
    
    x,y = q.popleft()
    
    r = deque()
    r.append([x,y])
    while r:
        xx,yy = r.popleft()
        
        f1(xx,yy,xx-1,yy)
        f1(xx,yy,xx+1,yy)
        f1(xx,yy,xx,yy-1)
        f1(xx,yy,xx,yy+1)
    
    for i in range(-2,3):
        for j in range(-2,3):
            f2(x,y,x+i,y+j)


print(reach[dx][dy])


Fixed submission:
from collections import deque
import time


def f1(x,y,xa,ya):
    if reach[xa][ya] == -1 or reach[xa][ya] > reach[x][y]:
         if c[xa][ya] == ".":
            reach[xa][ya] = reach[x][y]
            r.append([xa,ya])
            q.append([xa,ya])

            
            
def f2(x,y,xa,ya):
    if 0 <= xa <= h and 0 <= ya <= w:
    
        if reach[xa][ya] == -1 or reach[xa][ya] > reach[x][y] + 1:
            if c[xa][ya] == ".":
                reach[xa][ya] = reach[x][y] + 1
                q.append([xa,ya])

h,w = map(int,input().split())
cx, cy = map(int,input().split())
dx, dy = map(int,input().split())

t0 = time.time()

c = ["#"]*(h+2)
for i in range(1,h+1):
    c[i] = ["#"] + list(input()) + ["#"]
c[0]  = [0]*(w+2)
c[-1] = [0]*(w+2)

reach = [[-1 for j in range(w+2)] for i in range(h+2)]
q = deque([])

reach[cx][cy] = 0
q.append([cx,cy])

ans = 0

while q:
    
    if time.time() - t0 >= 1.5:
        break
    
    
    x,y = q.popleft()
    
    r = deque()
    r.append([x,y])
    while r:
        xx,yy = r.popleft()
        
        f1(xx,yy,xx-1,yy)
        f1(xx,yy,xx+1,yy)
        f1(xx,yy,xx,yy-1)
        f1(xx,yy,xx,yy+1)
    
    for i in range(-2,3):
        for j in range(-2,3):
            f2(x,y,x+i,y+j)


print(reach[dx][dy])

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

def f1(x,y,xa,ya):
    if reach[xa][ya] == -1 and c[xa][ya] == ".":
        reach[xa][ya] = reach[x][y]
        r.append([xa,ya])
        q.append([xa,ya])

def f2(x,y,xa,ya):
    if 0 <= xa <= h+1 and 0 <= ya <= w+1:
    
        if reach[xa][ya] == -1 or reach[xa][ya] > reach[x][y] + 1:
            if c[xa][ya] == ".":
                reach[xa][ya] = reach[x][y] + 1
                q.append([xa,ya])

h,w = map(int,input().split())
cx, cy = map(int,input().split())
dx, dy = map(int,input().split())

c = [0]*(h+2)
for i in range(1,h+1):
    c[i] = [0] + list(input()) + [0]
c[0]  = [0]*(w+2)
c[-1] = [0]*(w+2)

reach = [[-1 for j in range(w+2)] for i in range(h+2)]
q = deque([])

reach[cx][cy] = 0
q.append([cx,cy])

ans = 0

while q:
    x,y = q.pop()
    
    r = deque()
    r.append([x,y])
    while r:
        xx,yy = r.popleft()
        
        f1(xx,yy,xx-1,yy)
        f1(xx,yy,xx+1,yy)
        f1(xx,yy,xx,yy-1)
        f1(xx,yy,xx,yy+1)
    
    for i in range(-2,3):
        for j in range(-2,3):
            f2(x,y,x+i,y+j)
            
            if x == dx and y == dy:
                break


print(reach[dx][dy])


Fixed submission:
from collections import deque
import time


def f1(x,y,xa,ya):
    if reach[xa][ya] == -1 or reach[xa][ya] > reach[x][y]:
         if c[xa][ya] == ".":
            reach[xa][ya] = reach[x][y]
            r.append([xa,ya])
            q.append([xa,ya])

            
            
def f2(x,y,xa,ya):
    if 0 <= xa <= h and 0 <= ya <= w:
    
        if reach[xa][ya] == -1 or reach[xa][ya] > reach[x][y] + 1:
            if c[xa][ya] == ".":
                reach[xa][ya] = reach[x][y] + 1
                q.append([xa,ya])

h,w = map(int,input().split())
cx, cy = map(int,input().split())
dx, dy = map(int,input().split())

t0 = time.time()

c = ["#"]*(h+2)
for i in range(1,h+1):
    c[i] = ["#"] + list(input()) + ["#"]
c[0]  = [0]*(w+2)
c[-1] = [0]*(w+2)

reach = [[-1 for j in range(w+2)] for i in range(h+2)]
q = deque([])

reach[cx][cy] = 0
q.append([cx,cy])

ans = 0

while q:
    
    if time.time() - t0 >= 1.5:
        break
    
    
    x,y = q.popleft()
    
    r = deque()
    r.append([x,y])
    while r:
        xx,yy = r.popleft()
        
        f1(xx,yy,xx-1,yy)
        f1(xx,yy,xx+1,yy)
        f1(xx,yy,xx,yy-1)
        f1(xx,yy,xx,yy+1)
    
    for i in range(-2,3):
        for j in range(-2,3):
            f2(x,y,x+i,y+j)


print(reach[dx][dy])