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


input = lambda: sys.stdin.readline().rstrip()


if __name__ == "__main__":
    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())
    maze = ["#"*(W+4), "#"*(W+4)]
    maze += [list("##"+input()+"##") for _ in range(H)]
    maze += ["#"*(W+4), "#"*(W+4)]
    INF = 10**8
    mc = [[INF]*(W+4) for _ in range(H+4)]
    mc[ch][cw] = 0
    walk = [(1, 0), (0, 1), (-1, 0), (0, -1)]
    warp = [(y, x) for x in range(-2, 3) for y in range(-2, 3) if abs(y) + abs(x) > 1]
    que = deque()
    que.append((ch, cw, 0))
    while que:
        y, x, w = que.popleft()
        if mc[y][x] < w:
            continue
        for dy, dx in walk:
            ny = y + dy
            nx = x + dx
            if maze[ny][nx] == "." and mc[ny][nx] > w:
                mc[ny][nx] = w
                que.appendleft((ny, nx, w))
        for dy, dx in warp:
            ny = y + dy
            nx = x + dx
            if maze[ny][nx] == "." and mc[ny][nx] > w+1:
                mc[ny][nx] = w+1
                que.append((ny, nx, w+1))
    if mc[dh][dw] == INF:
        print(-1)
    else:
        print(mc[dh][dw])


Fixed submission:
import sys
from collections import deque


input = lambda: sys.stdin.readline().rstrip()


if __name__ == "__main__":
    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())
    maze = [list(input()) for _ in range(H)]
    INF = 10**8
    mc = [[INF]*W for _ in range(H)]
    mc[ch][cw] = 0
    walk_que = deque()
    walk_que.append((ch, cw, 0))
    while walk_que:
        y, x, w = walk_que.popleft()
        for ny, nx in [(y+1, x), (y-1, x), (y, x+1), (y, x-1)]:
            if H > ny >= 0 and W > nx >= 0 and mc[ny][nx] > w and maze[ny][nx] == ".":
                mc[ny][nx] = w
                walk_que.appendleft((ny, nx, w))
        for dy in range(-2, 3):
            ny = y + dy
            for dx in range(-2, 3):
                nx = x + dx
                if H > ny >= 0 and W > nx >= 0 and mc[ny][nx] > w+1 and maze[ny][nx] == ".":
                    mc[ny][nx] = w + 1
                    walk_que.append((ny, nx, w+1))
    if mc[dh][dw] == INF:
        print(-1)
    else:
        print(mc[dh][dw])

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


input = lambda: sys.stdin.readline().rstrip()


if __name__ == "__main__":
    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())
    maze = [list(input()) for _ in range(H)]
    INF = 10**8
    mc = [[INF]*W for _ in range(H)]
    mc[ch][cw] = 0
    walk = [(1, 0), (0, 1), (-1, 0), (0, -1)]
    warp = [(y, x) for x in range(-2, 3) for y in range(-2, 3) if abs(y) + abs(x) > 1]
    que = deque()
    que.append((ch, cw, 0))
    while que:
        y, x, w = que.popleft()
        if mc[y][x] < w:
            continue
        for dy, dx in walk:
            ny = y + dy
            nx = x + dx
            if H > ny >= 0 and W > nx >= 0 and mc[ny][nx] > w and maze[ny][nx] == ".":
                mc[ny][nx] = w
                que.appendleft((ny, nx, w))
        for dy, dx in warp:
            ny = y + dy
            nx = x + dx
            if H > ny >= 0 and W > nx >= 0 and mc[ny][nx] > w+1 and maze[ny][nx] == ".":
                mc[ny][nx] = w + 1
                que.append((ny, nx, w+1))
    if mc[dh][dw] == INF:
        print(-1)
    else:
        print(mc[dh][dw])


Fixed submission:
import sys
from collections import deque


input = lambda: sys.stdin.readline().rstrip()


if __name__ == "__main__":
    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())
    maze = [list(input()) for _ in range(H)]
    INF = 10**8
    mc = [[INF]*W for _ in range(H)]
    mc[ch][cw] = 0
    walk_que = deque()
    walk_que.append((ch, cw, 0))
    while walk_que:
        y, x, w = walk_que.popleft()
        for ny, nx in [(y+1, x), (y-1, x), (y, x+1), (y, x-1)]:
            if H > ny >= 0 and W > nx >= 0 and mc[ny][nx] > w and maze[ny][nx] == ".":
                mc[ny][nx] = w
                walk_que.appendleft((ny, nx, w))
        for dy in range(-2, 3):
            ny = y + dy
            for dx in range(-2, 3):
                nx = x + dx
                if H > ny >= 0 and W > nx >= 0 and mc[ny][nx] > w+1 and maze[ny][nx] == ".":
                    mc[ny][nx] = w + 1
                    walk_que.append((ny, nx, w+1))
    if mc[dh][dw] == INF:
        print(-1)
    else:
        print(mc[dh][dw])

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


input = lambda: sys.stdin.readline().rstrip()


if __name__ == "__main__":
    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())
    maze = [list(input()) for _ in range(H)]
    INF = 10**8
    mc = [[INF]*W for _ in range(H)]
    mc[ch][cw] = 0
    walk = [(1, 0), (0, 1), (-1, 0), (0, -1)]
    warp = [(y, x) for x in range(-2, 3) for y in range(-2, 3) if abs(y) + abs(x) > 1]
    que = deque()
    que.append((ch, cw, 0))
    while que:
        y, x, w = que.popleft()
        for dy, dx in walk:
            ny = y + dy
            nx = x + dx
            if H > ny >= 0 and W > nx >= 0 and mc[ny][nx] > w and maze[ny][nx] == ".":
                mc[ny][nx] = w
                que.appendleft((ny, nx, w))
        for dy, dx in warp:
            ny = y + dy
            nx = x + dx
            if H > ny >= 0 and W > nx >= 0 and mc[ny][nx] > w+1 and maze[ny][nx] == ".":
                mc[ny][nx] = w + 1
                que.append((ny, nx, w+1))
    if mc[dh][dw] == INF:
        print(-1)
    else:
        print(mc[dh][dw])


Fixed submission:
import sys
from collections import deque


input = lambda: sys.stdin.readline().rstrip()


if __name__ == "__main__":
    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())
    maze = [list(input()) for _ in range(H)]
    INF = 10**8
    mc = [[INF]*W for _ in range(H)]
    mc[ch][cw] = 0
    walk_que = deque()
    walk_que.append((ch, cw, 0))
    while walk_que:
        y, x, w = walk_que.popleft()
        for ny, nx in [(y+1, x), (y-1, x), (y, x+1), (y, x-1)]:
            if H > ny >= 0 and W > nx >= 0 and mc[ny][nx] > w and maze[ny][nx] == ".":
                mc[ny][nx] = w
                walk_que.appendleft((ny, nx, w))
        for dy in range(-2, 3):
            ny = y + dy
            for dx in range(-2, 3):
                nx = x + dx
                if H > ny >= 0 and W > nx >= 0 and mc[ny][nx] > w+1 and maze[ny][nx] == ".":
                    mc[ny][nx] = w + 1
                    walk_que.append((ny, nx, w+1))
    if mc[dh][dw] == INF:
        print(-1)
    else:
        print(mc[dh][dw])

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


input = lambda: sys.stdin.readline().rstrip()


if __name__ == "__main__":
    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())
    maze = [list(input()) for _ in range(H)]
    INF = 10**8
    mc = [[INF]*W for _ in range(H)]
    mc[ch][cw] = 0
    walk_que = deque()
    walk_que.append((ch, cw, 0))
    while walk_que:
        y, x, w = walk_que.popleft()
        for ny, nx in [(y+1, x), (y-1, x), (y, x+1), (y, x-1)]:
            if H > ny >= 0 and W > nx >= 0 and mc[ny][nx] > w and maze[ny][nx] == ".":
                mc[ny][nx] = w
                walk_que.appendleft((ny, nx, w))
        for dy in range(-2, 3):
            ny = y + dy
            for dx in range(-2, 3):
                nx = x + dx
                if H > ny >= 0 and W > nx >= 0 and mc[ny][nx] > w+1 and maze[ny][nx] == ".":
                    mc[ny][nx] = w + 1
                    walk_que.append((ny, nx, w+1))
    if mc[dh][dw] == INF:
        print(-1)
    else:
        print(mc[dh][dw])


Fixed submission:
import sys
from collections import deque


input = lambda: sys.stdin.readline().rstrip()


if __name__ == "__main__":
    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())
    maze = [list(input()) for _ in range(H)]
    INF = 10**8
    mc = [[INF]*W for _ in range(H)]
    mc[ch][cw] = 0
    walk_que = deque()
    walk_que.append((ch, cw, 0))
    while walk_que:
        y, x, w = walk_que.popleft()
        for ny, nx in [(y+1, x), (y-1, x), (y, x+1), (y, x-1)]:
            if H > ny >= 0 and W > nx >= 0 and mc[ny][nx] > w and maze[ny][nx] == ".":
                mc[ny][nx] = w
                walk_que.appendleft((ny, nx, w))
        for dy in range(-2, 3):
            ny = y + dy
            for dx in range(-2, 3):
                nx = x + dx
                if H > ny >= 0 and W > nx >= 0 and mc[ny][nx] > w+1 and maze[ny][nx] == ".":
                    mc[ny][nx] = w + 1
                    walk_que.append((ny, nx, w+1))
    if mc[dh][dw] == INF:
        print(-1)
    else:
        print(mc[dh][dw])

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


input = lambda: sys.stdin.readline().rstrip()


if __name__ == "__main__":
    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())
    maze = [list(input()) for _ in range(H)]
    INF = 10**8
    mc = [[INF]*W for _ in range(H)]
    walk = [(1, 0), (0, 1), (-1, 0), (0, -1)]
    warp = [
        (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)
    ]
    walk_que = deque()
    warp_que = deque()
    walk_que.append((ch, cw, 0))
    while walk_que:
        y, x, w = walk_que.popleft()
        mc[y][x] = w
        if y == dh and x == dw:
            break
        exit_wall = False
        for dy, dx in walk:
            ny = y + dy
            nx = x + dx
            if H > ny >= 0 and W > nx >= 0 and mc[ny][nx] == INF:
                if maze[ny][nx] == ".":
                    walk_que.append((ny, nx, w))
                else:
                    exit_wall = True
        if exit_wall:
            warp_que.append((y, x, w))
        if not walk_que:
            while warp_que:
                y, x, w = warp_que.popleft()
                for dy, dx in warp:
                    ny = y + dy
                    nx = x + dx
                    if H > ny >= 0 and W > nx >= 0 and mc[ny][nx] == INF and maze[ny][nx] == ".":
                        walk_que.append((ny, nx, w+1))
    if mc[dh][dw] == INF:
        print(-1)
    else:
        print(mc[dh][dw])


Fixed submission:
import sys
from collections import deque


input = lambda: sys.stdin.readline().rstrip()


if __name__ == "__main__":
    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())
    maze = [list(input()) for _ in range(H)]
    INF = 10**8
    mc = [[INF]*W for _ in range(H)]
    mc[ch][cw] = 0
    walk_que = deque()
    walk_que.append((ch, cw, 0))
    while walk_que:
        y, x, w = walk_que.popleft()
        for ny, nx in [(y+1, x), (y-1, x), (y, x+1), (y, x-1)]:
            if H > ny >= 0 and W > nx >= 0 and mc[ny][nx] > w and maze[ny][nx] == ".":
                mc[ny][nx] = w
                walk_que.appendleft((ny, nx, w))
        for dy in range(-2, 3):
            ny = y + dy
            for dx in range(-2, 3):
                nx = x + dx
                if H > ny >= 0 and W > nx >= 0 and mc[ny][nx] > w+1 and maze[ny][nx] == ".":
                    mc[ny][nx] = w + 1
                    walk_que.append((ny, nx, w+1))
    if mc[dh][dw] == INF:
        print(-1)
    else:
        print(mc[dh][dw])

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

input = lambda: sys.stdin.readline().rstrip()

if __name__ == "__main__":
    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())
    maze = [list(input()) for _ in range(H)]
    INF = 10**8
    mc = [[INF]*W for _ in range(H)]
    walk = [(1, 0), (0, 1), (-1, 0), (0, -1)]
    warp = [
        (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)
    ]
    walk_que = deque()
    warp_que = deque()
    walk_que.append((ch, cw, 0))
    while walk_que:
        y, x, w = walk_que.popleft()
        mc[y][x] = w
        if y == dh and x == dw:
            break
        exit_wall = False
        for dy, dx in walk:
            ny = y + dy
            nx = x + dx
            if H > ny >= 0 and W > nx >= 0 and mc[ny][nx] == INF:
                if maze[ny][nx] == ".":
                    walk_que.append((ny, nx, w))
                else:
                    exit_wall = True
        if exit_wall:
            warp_que.append((y, x, w))
        if not walk_que:
            while warp_que:
                y, x, w = warp_que.popleft()
                for dy, dx in warp:
                    ny = y + dy
                    nx = x + dx
                    if H > ny >= 0 and W > nx >= 0 and mc[ny][nx] == INF and maze[ny][nx] == ".":
                        walk_que.append((ny, nx, w+1))
    if mc[dh][dw] == INF:
        print(-1)
    else:
        print(mc[dh][dw])


Fixed submission:
import sys
from collections import deque


input = lambda: sys.stdin.readline().rstrip()


if __name__ == "__main__":
    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())
    maze = [list(input()) for _ in range(H)]
    INF = 10**8
    mc = [[INF]*W for _ in range(H)]
    mc[ch][cw] = 0
    walk_que = deque()
    walk_que.append((ch, cw, 0))
    while walk_que:
        y, x, w = walk_que.popleft()
        for ny, nx in [(y+1, x), (y-1, x), (y, x+1), (y, x-1)]:
            if H > ny >= 0 and W > nx >= 0 and mc[ny][nx] > w and maze[ny][nx] == ".":
                mc[ny][nx] = w
                walk_que.appendleft((ny, nx, w))
        for dy in range(-2, 3):
            ny = y + dy
            for dx in range(-2, 3):
                nx = x + dx
                if H > ny >= 0 and W > nx >= 0 and mc[ny][nx] > w+1 and maze[ny][nx] == ".":
                    mc[ny][nx] = w + 1
                    walk_que.append((ny, nx, w+1))
    if mc[dh][dw] == INF:
        print(-1)
    else:
        print(mc[dh][dw])

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


if __name__ == "__main__":
    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())
    maze = [list(input()) for _ in range(H)]
    INF = 10**8
    mc = [[INF]*W for _ in range(H)]
    walk = [(1, 0), (0, 1), (-1, 0), (0, -1)]
    warp = [
        (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)
    ]
    walk_que = deque()
    warp_que = deque()
    walk_que.append((ch, cw, 0))
    while walk_que:
        y, x, w = walk_que.popleft()
        mc[y][x] = w
        exit_wall = False
        for dy, dx in walk:
            ny = y + dy
            nx = x + dx
            if H > ny >= 0 and W > nx >= 0 and mc[ny][nx] == INF:
                if maze[ny][nx] == ".":
                    walk_que.append((ny, nx, w))
                else:
                    exit_wall = True
        if exit_wall:
            warp_que.append((y, x, w))
        if not walk_que:
            while warp_que:
                y, x, w = warp_que.popleft()
                for dy, dx in warp:
                    ny = y + dy
                    nx = x + dx
                    if H > ny >= 0 and W > nx >= 0 and mc[ny][nx] == INF and maze[ny][nx] == ".":
                        walk_que.append((ny, nx, w+1))
    if mc[dh][dw] == INF:
        print(-1)
    else:
        print(mc[dh][dw])


Fixed submission:
import sys
from collections import deque


input = lambda: sys.stdin.readline().rstrip()


if __name__ == "__main__":
    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())
    maze = [list(input()) for _ in range(H)]
    INF = 10**8
    mc = [[INF]*W for _ in range(H)]
    mc[ch][cw] = 0
    walk_que = deque()
    walk_que.append((ch, cw, 0))
    while walk_que:
        y, x, w = walk_que.popleft()
        for ny, nx in [(y+1, x), (y-1, x), (y, x+1), (y, x-1)]:
            if H > ny >= 0 and W > nx >= 0 and mc[ny][nx] > w and maze[ny][nx] == ".":
                mc[ny][nx] = w
                walk_que.appendleft((ny, nx, w))
        for dy in range(-2, 3):
            ny = y + dy
            for dx in range(-2, 3):
                nx = x + dx
                if H > ny >= 0 and W > nx >= 0 and mc[ny][nx] > w+1 and maze[ny][nx] == ".":
                    mc[ny][nx] = w + 1
                    walk_que.append((ny, nx, w+1))
    if mc[dh][dw] == INF:
        print(-1)
    else:
        print(mc[dh][dw])