Buggy python submission (verdict: Time Limit Exceeded):
#!/usr/bin/env python3
import sys
import collections
import itertools

def main():
    input = sys.stdin.readline
    h, w = map(int, input().split())
    ch, cw = map(lambda x:int(x) - 1, input().split())
    dh, dw = map(lambda x:int(x) - 1, input().split())
    s = [list(input().rstrip()) for _ in range(h)]
    
    que = collections.deque()
    que.append((0, ch, cw))
    cost = [[-1] * w for _ in range(h)]
    cost[ch][cw] = 0
    
    while que:
        c, py, px = que.popleft()
        if cost[py][px] == -1:
            cost[py][px] = c
        
        for dy, dx in [(-1, 0), (0, -1), (1, 0), (0, 1)]:
            ny, nx = py + dy, px + dx
            if 0 <= ny < h and 0 <= nx < w and s[ny][nx] == "." and cost[ny][nx] == -1:
                que.appendleft((c, ny, nx))
        
        for ny, nx in itertools.product(range(py - 2, py + 3), range(px - 2, px + 3)):
            if 0 <= ny < h and 0 <= nx < w and s[ny][nx] == "." and cost[ny][nx] == -1:
                que.append((c + 1, ny, nx))
    
    print(cost[dh][dw])

    
if __name__ == '__main__':
    main()


Fixed submission:
import collections
import itertools

h, w = map(int, input().split())
sy, sx = map(lambda x:int(x) - 1, input().split())
gy, gx = map(lambda x:int(x) - 1, input().split())
maze = [list(input()) for _ in range(h)]

seen = [[-1] * w for _ in range(h)]
seen[sy][sx] = 0
que = collections.deque()
que.append((sy, sx))
tmp2 = [(sy, sx)]
cnt = 0
while True:
    tmp1 = []
    for sy, sx in tmp2:
        if maze[sy][sx] == ".":
            que.append((sy,sx))
            tmp1.append((sy, sx))
            while que:
                py, px = que.popleft()
                for dy, dx in [(-1, 0), (0, -1), (1, 0), (0, 1)]:
                    ny = py + dy
                    nx = px + dx
                    if 0 <= ny < h and 0 <= nx < w and maze[ny][nx] == "." and seen[ny][nx] == -1:
                        seen[ny][nx] = cnt
                        que.append((ny, nx))
                        tmp1.append((ny, nx))
                        maze[sy][sx] = "#"
                        
    if seen[gy][gx] != -1:
        break

    flag = True
    d = [-2, -1, 0, 1, 2]
    tmp2 = []
    for py, px in tmp1:
        for i in range(5):
            for j in range(5):
                ny = py + d[i]
                nx = px + d[j]
                if 0 <= ny < h and 0 <= nx < w and maze[ny][nx] == "." and seen[ny][nx] == -1:
                    seen[ny][nx] = cnt + 1
                    que.append((ny, nx))
                    flag = False
                    tmp2.append((ny, nx))
    cnt += 1
    if flag:
        break
    if seen[gy][gx] != -1:
        break

print(seen[gy][gx])

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

h, w = map(int, input().split())
sy, sx = map(lambda x:int(x) - 1, input().split())
gy, gx = map(lambda x:int(x) - 1, input().split())
maze = [list(input()) for _ in range(h)]

seen = [[-1] * w for _ in range(h)]
seen[sy][sx] = 0
que = collections.deque()
que.append((sy, sx))

cnt = 0
while True:
    if seen[gy][gx] != -1:
        break
    
    while que:
        py, px = que.popleft()
        for dy, dx in [(-1, 0), (0, -1), (1, 0), (0, 1)]:
            ny = py + dy
            nx = px + dx
            if 0 <= ny < h and 0 <= nx < w and maze[ny][nx] == "." and seen[ny][nx] == -1:
                seen[ny][nx] = cnt
                que.append((ny, nx))
    
    flag = True
    d = [-2, -1, 0, 1, 2]
    for py in range(h):
        for px in range(w):
            if seen[py][px] == cnt:
                for i in range(5):
                    for j in range(5):
                        ny = py + d[i]
                        nx = px + d[j]
                        if 0 <= ny < h and 0 <= nx < w and maze[ny][nx] == "." and seen[ny][nx] == -1:
                            seen[ny][nx] = cnt + 1
                            que.append((ny, nx))
                            flag = False
    cnt += 1
    if flag:
        break

print(seen[gy][gx])

Fixed submission:
import collections
import itertools

h, w = map(int, input().split())
sy, sx = map(lambda x:int(x) - 1, input().split())
gy, gx = map(lambda x:int(x) - 1, input().split())
maze = [list(input()) for _ in range(h)]

seen = [[-1] * w for _ in range(h)]
seen[sy][sx] = 0
que = collections.deque()
que.append((sy, sx))
tmp2 = [(sy, sx)]
cnt = 0
while True:
    tmp1 = []
    for sy, sx in tmp2:
        if maze[sy][sx] == ".":
            que.append((sy,sx))
            tmp1.append((sy, sx))
            while que:
                py, px = que.popleft()
                for dy, dx in [(-1, 0), (0, -1), (1, 0), (0, 1)]:
                    ny = py + dy
                    nx = px + dx
                    if 0 <= ny < h and 0 <= nx < w and maze[ny][nx] == "." and seen[ny][nx] == -1:
                        seen[ny][nx] = cnt
                        que.append((ny, nx))
                        tmp1.append((ny, nx))
                        maze[sy][sx] = "#"
                        
    if seen[gy][gx] != -1:
        break

    flag = True
    d = [-2, -1, 0, 1, 2]
    tmp2 = []
    for py, px in tmp1:
        for i in range(5):
            for j in range(5):
                ny = py + d[i]
                nx = px + d[j]
                if 0 <= ny < h and 0 <= nx < w and maze[ny][nx] == "." and seen[ny][nx] == -1:
                    seen[ny][nx] = cnt + 1
                    que.append((ny, nx))
                    flag = False
                    tmp2.append((ny, nx))
    cnt += 1
    if flag:
        break
    if seen[gy][gx] != -1:
        break

print(seen[gy][gx])