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

h, w = map(int, input().split())
cx, cy = map(lambda x: int(x) - 1, input().split())
dx, dy = map(lambda x: int(x) - 1, input().split())
s = [[i for i in input()] for _ in range(h)]
c = [[10**6] * w for _ in range(h)]

d = ((1, 0), (-1, 0), (0, 1), (0, -1))
q = deque([(cx, cy)])

c[cx][cy] = 0

while q:
    x, y = q.pop()
    cp = c[x][y]
    if (x, y) == (dx, dy):
        c[x][y] = cp
        break
    for i, j in d:
        nx = x + i
        ny = y + j
        if 0 <= nx < h and 0 <= ny < w and s[nx][ny] != "#" and c[nx][ny] > cp:
            q.append((nx, ny))
            c[nx][ny] = cp
    cp += 1
    for i in range(-2, 3):
        for j in range(-2, 3):
            nx = x + i
            ny = y + j
            if 0 <= nx < h and 0 <= ny < w and s[nx][ny] != "#" and c[nx][
                    ny] > cp:
                c[nx][ny] = cp
                q.appendleft((nx, ny))
print(-1 * (c[dx][dy] == 10**6) or c[dx][dy])


Fixed submission:
#!/usr/bin/env python3
import heapq

h, w = map(int, input().split())
cx, cy = map(lambda x: int(x) - 1, input().split())
dx, dy = map(lambda x: int(x) - 1, input().split())
s = [input() for _ in range(h)]
c = [[10**6] * w for _ in range(h)]


def bfs():
    d = ((1, 0), (-1, 0), (0, 1), (0, -1))
    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),
    )
    hp = []

    heapq.heappush(hp, (0, (cx, cy)))
    c[cx][cy] = 0

    while hp:
        cp, (
            x,
            y,
        ) = heapq.heappop(hp)
        if (x, y) == (dx, dy):
            c[x][y] = cp
            break
        for i in range(4):
            nx = x + d[i][0]
            ny = y + d[i][1]
            if 0 <= nx < h and 0 <= ny < w and s[nx][ny] != "#" and c[nx][
                    ny] > cp:
                heapq.heappush(hp, (cp, (nx, ny)))
                c[nx][ny] = cp
        cp += 1
        for i in range(20):
            nx = x + d2[i][0]
            ny = y + d2[i][1]
            if 0 <= nx < h and 0 <= ny < w and s[nx][ny] != "#" and c[nx][
                    ny] > cp:
                c[nx][ny] = cp
                heapq.heappush(hp, (cp, (nx, ny)))

    return c[dx][dy] if c[dx][dy] < 10**6 else -1


print(bfs())

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

h, w = map(int, input().split())
cx, cy = map(lambda x: int(x) - 1, input().split())
dx, dy = map(lambda x: int(x) - 1, input().split())
s = [input() for _ in range(h)]
c = [[10**6] * w for _ in range(h)]


def bfs():
    d = ((1, 0), (-1, 0), (0, 1), (0, -1))
    q = deque([(cx, cy)])

    c[cx][cy] = 0

    while q:
        x, y = q.pop()
        cp = c[x][y]
        if (x, y) == (dx, dy):
            c[x][y] = cp
            break
        for i, j in d:
            nx = x + i
            ny = y + j
            if 0 <= nx < h and 0 <= ny < w and s[nx][ny] != "#" and c[nx][
                    ny] > cp:
                q.append((nx, ny))
                c[nx][ny] = cp
        cp += 1
        for i in range(-2, 3):
            for j in range(-2, 3):
                nx = x + i
                ny = y + j
                if 0 <= nx < h and 0 <= ny < w and s[nx][ny] != "#" and c[nx][
                        ny] > cp:
                    c[nx][ny] = cp
                    q.appendleft((nx, ny))

    return -1 * (c[dx][dy] == 10**6) or c[dx][dy]


print(bfs())


Fixed submission:
#!/usr/bin/env python3
import heapq

h, w = map(int, input().split())
cx, cy = map(lambda x: int(x) - 1, input().split())
dx, dy = map(lambda x: int(x) - 1, input().split())
s = [input() for _ in range(h)]
c = [[10**6] * w for _ in range(h)]


def bfs():
    d = ((1, 0), (-1, 0), (0, 1), (0, -1))
    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),
    )
    hp = []

    heapq.heappush(hp, (0, (cx, cy)))
    c[cx][cy] = 0

    while hp:
        cp, (
            x,
            y,
        ) = heapq.heappop(hp)
        if (x, y) == (dx, dy):
            c[x][y] = cp
            break
        for i in range(4):
            nx = x + d[i][0]
            ny = y + d[i][1]
            if 0 <= nx < h and 0 <= ny < w and s[nx][ny] != "#" and c[nx][
                    ny] > cp:
                heapq.heappush(hp, (cp, (nx, ny)))
                c[nx][ny] = cp
        cp += 1
        for i in range(20):
            nx = x + d2[i][0]
            ny = y + d2[i][1]
            if 0 <= nx < h and 0 <= ny < w and s[nx][ny] != "#" and c[nx][
                    ny] > cp:
                c[nx][ny] = cp
                heapq.heappush(hp, (cp, (nx, ny)))

    return c[dx][dy] if c[dx][dy] < 10**6 else -1


print(bfs())

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

h, w = map(int, input().split())
cx, cy = map(lambda x: int(x) - 1, input().split())
dx, dy = map(lambda x: int(x) - 1, input().split())
s = [input() for _ in range(h)]
c = [[10**6] * w for _ in range(h)]


def bfs():
    d = ((1, 0), (-1, 0), (0, 1), (0, -1))
    q = deque([(cx, cy)])

    c[cx][cy] = 0

    while q:
        x, y = q.popleft()
        cp = c[x][y]
        if (x, y) == (dx, dy):
            c[x][y] = cp
            break
        for i, j in d:
            nx = x + i
            ny = y + j
            if 0 <= nx < h and 0 <= ny < w and s[nx][ny] != "#" and c[nx][
                    ny] > cp:
                q.appendleft((nx, ny))
                c[nx][ny] = cp
        cp += 1
        for i in range(-2, 3):
            for j in range(-2, 3):
                nx = x + i
                ny = y + j
                if 0 <= nx < h and 0 <= ny < w and s[nx][ny] != "#" and c[nx][
                        ny] > cp:
                    c[nx][ny] = cp
                    q.append((nx, ny))

    return -1 * (c[dx][dy] == 10**6) or c[dx][dy]


print(bfs())


Fixed submission:
#!/usr/bin/env python3
import heapq

h, w = map(int, input().split())
cx, cy = map(lambda x: int(x) - 1, input().split())
dx, dy = map(lambda x: int(x) - 1, input().split())
s = [input() for _ in range(h)]
c = [[10**6] * w for _ in range(h)]


def bfs():
    d = ((1, 0), (-1, 0), (0, 1), (0, -1))
    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),
    )
    hp = []

    heapq.heappush(hp, (0, (cx, cy)))
    c[cx][cy] = 0

    while hp:
        cp, (
            x,
            y,
        ) = heapq.heappop(hp)
        if (x, y) == (dx, dy):
            c[x][y] = cp
            break
        for i in range(4):
            nx = x + d[i][0]
            ny = y + d[i][1]
            if 0 <= nx < h and 0 <= ny < w and s[nx][ny] != "#" and c[nx][
                    ny] > cp:
                heapq.heappush(hp, (cp, (nx, ny)))
                c[nx][ny] = cp
        cp += 1
        for i in range(20):
            nx = x + d2[i][0]
            ny = y + d2[i][1]
            if 0 <= nx < h and 0 <= ny < w and s[nx][ny] != "#" and c[nx][
                    ny] > cp:
                c[nx][ny] = cp
                heapq.heappush(hp, (cp, (nx, ny)))

    return c[dx][dy] if c[dx][dy] < 10**6 else -1


print(bfs())

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

h, w = map(int, input().split())
cx, cy = map(lambda x: int(x) - 1, input().split())
dx, dy = map(lambda x: int(x) - 1, input().split())
s = [input() for _ in range(h)]
c = [[10**6] * w for _ in range(h)]


def bfs():
    d = ((1, 0), (-1, 0), (0, 1), (0, -1))
    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),
    )
    hp = []

    heapq.heappush(hp, (0, (cx, cy)))
    c[cx][cy] = 0

    while hp:
        cp, (
            x,
            y,
        ) = heapq.heappop(hp)
        if (x, y) == (dx, dy):
            c[x][y] = cp
            break
        for i in range(4):
            nx = x + d[i][0]
            ny = y + d[i][1]
            if 0 <= nx < h and 0 <= ny < w and s[nx][ny] != "#" and c[nx][
                    ny] > cp:
                heapq.heappush(hp, (cp, (nx, ny)))
                c[nx][ny] = cp
        cp += 1
        for i in range(20):
            nx = x + d2[i][0]
            ny = y + d2[i][1]
            if 0 <= nx < h and 0 <= ny < w and s[nx][ny] != "#" and c[nx][
                    ny] > cp:
                c[nx][ny] = cp
                heapq.heappush(hp, (cp, (nx, ny)))

    return c[dx][dy] if c[dx][dy] < 10**6 else -1


print(bfs())


Fixed submission:
#!/usr/bin/env python3
import heapq

h, w = map(int, input().split())
cx, cy = map(lambda x: int(x) - 1, input().split())
dx, dy = map(lambda x: int(x) - 1, input().split())
s = [input() for _ in range(h)]
c = [[10**6] * w for _ in range(h)]


def bfs():
    d = ((1, 0), (-1, 0), (0, 1), (0, -1))
    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),
    )
    hp = []

    heapq.heappush(hp, (0, (cx, cy)))
    c[cx][cy] = 0

    while hp:
        cp, (
            x,
            y,
        ) = heapq.heappop(hp)
        if (x, y) == (dx, dy):
            c[x][y] = cp
            break
        for i in range(4):
            nx = x + d[i][0]
            ny = y + d[i][1]
            if 0 <= nx < h and 0 <= ny < w and s[nx][ny] != "#" and c[nx][
                    ny] > cp:
                heapq.heappush(hp, (cp, (nx, ny)))
                c[nx][ny] = cp
        cp += 1
        for i in range(20):
            nx = x + d2[i][0]
            ny = y + d2[i][1]
            if 0 <= nx < h and 0 <= ny < w and s[nx][ny] != "#" and c[nx][
                    ny] > cp:
                c[nx][ny] = cp
                heapq.heappush(hp, (cp, (nx, ny)))

    return c[dx][dy] if c[dx][dy] < 10**6 else -1


print(bfs())