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

input = sys.stdin.readline

h,w = map(int,input().split())
ch,cw = map(int,input().split())
dh,dw = map(int,input().split())
s = [input() for _ in range(h)]

v = [[-1] * w for _ in range(h)]
d = [(0,1), (0,-1), (1,0), (-1,0)]
d2 = [(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)]

v[ch-1][cw-1] = 0

q = deque([(ch-1, cw-1)])
q2 = deque([(ch-1, cw-1)])
q3 = deque([])
tmp = 0

while True:
    while q:
        i,j = q.popleft()
        for ii,jj in d:
            if 0 <= i + ii < h and 0 <= j + jj < w:
                if v[i+ii][j+jj] == -1 and s[i+ii][j+jj] == '.':
                    v[i+ii][j+jj] = tmp
                    q.append((i+ii,j+jj))
                    q2.append((i+ii,j+jj))

    for i,j in q2:
        for ii,jj in d2:
            if v[i][j] == tmp and 0 <= i + ii < h and 0 <= j + jj < w:
                if v[i+ii][j+jj] == -1 and s[i+ii][j+jj] == '.':
                    v[i+ii][j+jj] = tmp+1
                    q.append((i+ii,j+jj))
                    q3.append((i+ii,j+jj))
    if not q:
        break
    tmp += 1
    q2 = copy.copy(q3)

print(v[dh-1][dw-1])


Fixed submission:
import sys
from collections import deque
import copy

input = sys.stdin.readline

h,w = map(int,input().split())
ch,cw = map(int,input().split())
dh,dw = map(int,input().split())
s = [input() for _ in range(h)]

v = [[-1] * w for _ in range(h)]
d = [(0,1), (0,-1), (1,0), (-1,0)]
d2 = [(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)]

v[ch-1][cw-1] = 0

q = deque([(ch-1, cw-1)])
q2 = [(ch-1, cw-1)]
tmp = 0

while True:
    while q:
        i,j = q.popleft()
        for ii,jj in d:
            if 0 <= i + ii < h and 0 <= j + jj < w:
                if v[i+ii][j+jj] == -1 and s[i+ii][j+jj] == '.':
                    v[i+ii][j+jj] = tmp
                    q.append((i+ii,j+jj))
                    q2.append((i+ii,j+jj))

    cnt = 0
    for k in range(len(q2)):
        i,j = q2[k][0], q2[k][1]
        for ii,jj in d2:
            if v[i][j] == tmp and 0 <= i + ii < h and 0 <= j + jj < w:
                if v[i+ii][j+jj] == -1 and s[i+ii][j+jj] == '.':
                    v[i+ii][j+jj] = tmp+1
                    q.append((i+ii,j+jj))
                    q2.append((i+ii,j+jj))
                    cnt += 1
    if not q:
        break
    tmp += 1
    q2 = q2[-cnt:]
print(v[dh-1][dw-1])

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

input = sys.stdin.readline

h,w = map(int,input().split())
ch,cw = map(int,input().split())
dh,dw = map(int,input().split())
s = [input() for _ in range(h)]

v = [[-1] * w for _ in range(h)]
d = [(0,1), (0,-1), (1,0), (-1,0)]
d2 = [(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)]

v[ch-1][cw-1] = 0

q = deque([(ch-1, cw-1)])
q2 = [(ch-1, cw-1)]
q3 = []
tmp = 0

while True:
    while q:
        i,j = q.popleft()
        for ii,jj in d:
            if 0 <= i + ii < h and 0 <= j + jj < w:
                if v[i+ii][j+jj] == -1 and s[i+ii][j+jj] == '.':
                    v[i+ii][j+jj] = tmp
                    q.append((i+ii,j+jj))
                    q2.append((i+ii,j+jj))

    for i,j in q2:
        for ii,jj in d2:
            if v[i][j] == tmp and 0 <= i + ii < h and 0 <= j + jj < w:
                if v[i+ii][j+jj] == -1 and s[i+ii][j+jj] == '.':
                    v[i+ii][j+jj] = tmp+1
                    q.append((i+ii,j+jj))
                    q3.append((i+ii,j+jj))
    if not q:
        break
    tmp += 1
    q2 = copy.copy(q3)

print(v[dh-1][dw-1])


Fixed submission:
import sys
from collections import deque
import copy

input = sys.stdin.readline

h,w = map(int,input().split())
ch,cw = map(int,input().split())
dh,dw = map(int,input().split())
s = [input() for _ in range(h)]

v = [[-1] * w for _ in range(h)]
d = [(0,1), (0,-1), (1,0), (-1,0)]
d2 = [(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)]

v[ch-1][cw-1] = 0

q = deque([(ch-1, cw-1)])
q2 = [(ch-1, cw-1)]
tmp = 0

while True:
    while q:
        i,j = q.popleft()
        for ii,jj in d:
            if 0 <= i + ii < h and 0 <= j + jj < w:
                if v[i+ii][j+jj] == -1 and s[i+ii][j+jj] == '.':
                    v[i+ii][j+jj] = tmp
                    q.append((i+ii,j+jj))
                    q2.append((i+ii,j+jj))

    cnt = 0
    for k in range(len(q2)):
        i,j = q2[k][0], q2[k][1]
        for ii,jj in d2:
            if v[i][j] == tmp and 0 <= i + ii < h and 0 <= j + jj < w:
                if v[i+ii][j+jj] == -1 and s[i+ii][j+jj] == '.':
                    v[i+ii][j+jj] = tmp+1
                    q.append((i+ii,j+jj))
                    q2.append((i+ii,j+jj))
                    cnt += 1
    if not q:
        break
    tmp += 1
    q2 = q2[-cnt:]
print(v[dh-1][dw-1])

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())
s = [input() for _ in range(h)]

v = [[-1] * w for _ in range(h)]
d = [(0,1), (0,-1), (1,0), (-1,0)]
d2 = [(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)]

v[ch-1][cw-1] = 0

q = deque([(ch-1, cw-1)])
tmp = 0

while True:
    while q:
        i,j = q.popleft()
        for ii,jj in d:
            if 0 <= i + ii < h and 0 <= j + jj < w:
                if v[i+ii][j+jj] == -1 and s[i+ii][j+jj] == '.':
                    v[i+ii][j+jj] = tmp
                    q.append((i+ii,j+jj))

    for i in range(h):
        for j in range(w):
            for ii,jj in d2:
                if v[i][j] == tmp and 0 <= i + ii < h and 0 <= j + jj < w:
                    if v[i+ii][j+jj] == -1 and s[i+ii][j+jj] == '.':
                        v[i+ii][j+jj] = tmp+1
                        q.append((i+ii,j+jj))
    if not q:
        break
    tmp += 1

print(v[dh-1][dw-1])


Fixed submission:
import sys
from collections import deque
import copy

input = sys.stdin.readline

h,w = map(int,input().split())
ch,cw = map(int,input().split())
dh,dw = map(int,input().split())
s = [input() for _ in range(h)]

v = [[-1] * w for _ in range(h)]
d = [(0,1), (0,-1), (1,0), (-1,0)]
d2 = [(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)]

v[ch-1][cw-1] = 0

q = deque([(ch-1, cw-1)])
q2 = [(ch-1, cw-1)]
tmp = 0

while True:
    while q:
        i,j = q.popleft()
        for ii,jj in d:
            if 0 <= i + ii < h and 0 <= j + jj < w:
                if v[i+ii][j+jj] == -1 and s[i+ii][j+jj] == '.':
                    v[i+ii][j+jj] = tmp
                    q.append((i+ii,j+jj))
                    q2.append((i+ii,j+jj))

    cnt = 0
    for k in range(len(q2)):
        i,j = q2[k][0], q2[k][1]
        for ii,jj in d2:
            if v[i][j] == tmp and 0 <= i + ii < h and 0 <= j + jj < w:
                if v[i+ii][j+jj] == -1 and s[i+ii][j+jj] == '.':
                    v[i+ii][j+jj] = tmp+1
                    q.append((i+ii,j+jj))
                    q2.append((i+ii,j+jj))
                    cnt += 1
    if not q:
        break
    tmp += 1
    q2 = q2[-cnt:]
print(v[dh-1][dw-1])