Buggy python submission (verdict: Time Limit Exceeded):
from collections import deque
def bfs():
    move=[[1,0],[0,1],[-1,0],[0,-1]]
    
    queue=deque()

    queue.append((0,(sy,sx))) #queue=deque([[sy,sx]])でもよい
    visited[sy][sx]=0 #スタート地点の距離は0
    while queue:
        cnt,(y,x)=queue.popleft()
        
        
        for dy,dx in move:
            my,mx=y+dy,x+dx 
            if my<0 or my>=tate:
                continue
            if mx<0 or mx>=yoko:
                continue
            if maze[my][mx]=="#":
                continue
            if visited[my][mx]>cnt:
                queue.append((cnt,(my,mx)))
                visited[my][mx]=cnt # visitedは距離も兼ねてる
        for my in range(y-2,y+3):
            for mx in range(x-2,x+3):
                if my<0 or my>=tate:
                    continue
                if mx<0 or mx>=yoko:
                    continue
                if maze[my][mx]=="#":
                    continue
                if visited[my][mx]>cnt+1:
                    queue.append((cnt+1,(my,mx)))
                    visited[my][mx]=cnt+1
    if visited[gy][gx]==inf:
        print(-1)
    else:
        print(visited[gy][gx])


tate,yoko=map(int,input().split())
sy,sx=map(int,input().split())
gy,gx=map(int,input().split())
sy,sx,gy,gx=sy-1,sx-1,gy-1,gx-1
maze=[]
inf=float('inf')
visited=[[inf]*yoko for i in range(tate)]

for i in range(tate):
    line=list(input())
    maze.append(line)
bfs()




Fixed submission:
from collections import deque
def bfs():
    move=[[1,0],[0,1],[-1,0],[0,-1]]
    
    queue=deque()
    queue.append([sy,sx]) #queue=deque([[sy,sx]])でもよい
    visited[sy][sx]=0 #スタート地点の距離は0
    while queue:
        y,x=queue.popleft()
        cnt=visited[y][x]
        
        for dy,dx in move:
            my,mx=y+dy,x+dx 
            if my<0 or my>=tate:
                continue
            if mx<0 or mx>=yoko:
                continue
            if maze[my][mx]=="#":
                continue
            if visited[my][mx]>cnt:
                queue.appendleft([my,mx])
                visited[my][mx]=cnt # visitedは距離も兼ねてる
        for my in range(y-2,y+3):
            for mx in range(x-2,x+3):
                if my<0 or my>=tate:
                    continue
                if mx<0 or mx>=yoko:
                    continue
                if maze[my][mx]=="#":
                    continue
                if visited[my][mx]>cnt+1:
                    queue.append([my,mx])
                    visited[my][mx]=cnt+1
    if visited[gy][gx]==inf:
        print(-1)
    else:
        print(visited[gy][gx])


tate,yoko=map(int,input().split())
sy,sx=map(int,input().split())
gy,gx=map(int,input().split())
sy,sx,gy,gx=sy-1,sx-1,gy-1,gx-1
maze=[]
inf=float('inf')
visited=[[inf]*yoko for i in range(tate)]

for i in range(tate):
    line=list(input())
    maze.append(line)
bfs()

Buggy python submission (verdict: Time Limit Exceeded):
from collections import deque
def bfs():
    move=[[1,0],[0,1],[-1,0],[0,-1]]
    
    queue=deque()
    queue.append([sy,sx]) #queue=deque([[sy,sx]])でもよい
    visited[sy][sx]=0 #スタート地点の距離は0
    while queue:
        y,x=queue.popleft()
        cnt=visited[y][x]
        
        for dy,dx in move:
            my,mx=y+dy,x+dx 
            if my<0 or my>=tate:
                continue
            if mx<0 or mx>=yoko:
                continue
            if maze[my][mx]=="#":
                continue
            if visited[my][mx]>cnt:
                queue.append([my,mx])
                visited[my][mx]=cnt # visitedは距離も兼ねてる
        for my in range(y-2,y+3):
            for mx in range(x-2,x+3):
                if my<0 or my>=tate:
                    continue
                if mx<0 or mx>=yoko:
                    continue
                if maze[my][mx]=="#":
                    continue
                if visited[my][mx]>cnt+1:
                    queue.append([my,mx])
                    visited[my][mx]=cnt+1
    if visited[gy][gx]==inf:
        print(-1)
    else:
        print(visited[gy][gx])


tate,yoko=map(int,input().split())
sy,sx=map(int,input().split())
gy,gx=map(int,input().split())
sy,sx,gy,gx=sy-1,sx-1,gy-1,gx-1
maze=[]
inf=float('inf')
visited=[[inf]*yoko for i in range(tate)]

for i in range(tate):
    line=list(input())
    maze.append(line)
bfs()




Fixed submission:
from collections import deque
def bfs():
    move=[[1,0],[0,1],[-1,0],[0,-1]]
    
    queue=deque()
    queue.append([sy,sx]) #queue=deque([[sy,sx]])でもよい
    visited[sy][sx]=0 #スタート地点の距離は0
    while queue:
        y,x=queue.popleft()
        cnt=visited[y][x]
        
        for dy,dx in move:
            my,mx=y+dy,x+dx 
            if my<0 or my>=tate:
                continue
            if mx<0 or mx>=yoko:
                continue
            if maze[my][mx]=="#":
                continue
            if visited[my][mx]>cnt:
                queue.appendleft([my,mx])
                visited[my][mx]=cnt # visitedは距離も兼ねてる
        for my in range(y-2,y+3):
            for mx in range(x-2,x+3):
                if my<0 or my>=tate:
                    continue
                if mx<0 or mx>=yoko:
                    continue
                if maze[my][mx]=="#":
                    continue
                if visited[my][mx]>cnt+1:
                    queue.append([my,mx])
                    visited[my][mx]=cnt+1
    if visited[gy][gx]==inf:
        print(-1)
    else:
        print(visited[gy][gx])


tate,yoko=map(int,input().split())
sy,sx=map(int,input().split())
gy,gx=map(int,input().split())
sy,sx,gy,gx=sy-1,sx-1,gy-1,gx-1
maze=[]
inf=float('inf')
visited=[[inf]*yoko for i in range(tate)]

for i in range(tate):
    line=list(input())
    maze.append(line)
bfs()

Buggy python submission (verdict: Time Limit Exceeded):
from collections import deque
def bfs():
    move=[[1,0],[0,1],[-1,0],[0,-1]]
    
    queue=deque()
    queue.append([sy,sx]) #queue=deque([[sy,sx]])でもよい
    visited[sy][sx]=0 #スタート地点の距離は0
    while queue:
        y,x=queue.popleft()
        cnt=visited[y][x]
        
        for dy,dx in move:
            my,mx=y+dy,x+dx 
            if not(0<=my<tate and 0<=mx<yoko):
                continue
            if maze[my][mx]=="#":
                continue
            if visited[my][mx]>cnt:
                queue.append([my,mx])
                visited[my][mx]=cnt # visitedは距離も兼ねてる
        for my in range(y-2,y+3):
            for mx in range(x-2,x+3):
                if not(0<=my<tate and 0<=mx<yoko):
                    continue
                if maze[my][mx]=="#":
                    continue
                if visited[my][mx]>cnt+1:
                    queue.append([my,mx])
                    visited[my][mx]=cnt+1
    if visited[gy][gx]==inf:
        print(-1)
    else:
        print(visited[gy][gx])


tate,yoko=map(int,input().split())
sy,sx=map(int,input().split())
gy,gx=map(int,input().split())
sy,sx,gy,gx=sy-1,sx-1,gy-1,gx-1
maze=[]
inf=float('inf')
visited=[[inf]*yoko for i in range(tate)]

for i in range(tate):
    line=list(input())
    maze.append(line)
bfs()




Fixed submission:
from collections import deque
def bfs():
    move=[[1,0],[0,1],[-1,0],[0,-1]]
    
    queue=deque()
    queue.append([sy,sx]) #queue=deque([[sy,sx]])でもよい
    visited[sy][sx]=0 #スタート地点の距離は0
    while queue:
        y,x=queue.popleft()
        cnt=visited[y][x]
        
        for dy,dx in move:
            my,mx=y+dy,x+dx 
            if my<0 or my>=tate:
                continue
            if mx<0 or mx>=yoko:
                continue
            if maze[my][mx]=="#":
                continue
            if visited[my][mx]>cnt:
                queue.appendleft([my,mx])
                visited[my][mx]=cnt # visitedは距離も兼ねてる
        for my in range(y-2,y+3):
            for mx in range(x-2,x+3):
                if my<0 or my>=tate:
                    continue
                if mx<0 or mx>=yoko:
                    continue
                if maze[my][mx]=="#":
                    continue
                if visited[my][mx]>cnt+1:
                    queue.append([my,mx])
                    visited[my][mx]=cnt+1
    if visited[gy][gx]==inf:
        print(-1)
    else:
        print(visited[gy][gx])


tate,yoko=map(int,input().split())
sy,sx=map(int,input().split())
gy,gx=map(int,input().split())
sy,sx,gy,gx=sy-1,sx-1,gy-1,gx-1
maze=[]
inf=float('inf')
visited=[[inf]*yoko for i in range(tate)]

for i in range(tate):
    line=list(input())
    maze.append(line)
bfs()

Buggy python submission (verdict: Time Limit Exceeded):
from collections import deque
def bfs():
    move=[[1,0],[0,1],[-1,0],[0,-1]]
    
    queue=deque()
    queue.append([sy,sx]) #queue=deque([[sy,sx]])でもよい
    visited[sy][sx]=0 #スタート地点の距離は0
    while queue:
        y,x=queue.popleft()
        cnt=visited[y][x]
        
        for dy,dx in move:
            my,mx=y+dy,x+dx 
            if (0<=my<tate and 0<=mx<yoko) and maze[my][mx]=="." and visited[my][mx]>cnt:
                queue.append([my,mx])
                visited[my][mx]=cnt # visitedは距離も兼ねてる
        for my in range(y-2,y+3):
            for mx in range(x-2,x+3):
                if (0<=my<tate and 0<=mx<yoko) and maze[my][mx]==".":
                    if visited[my][mx]>cnt+1:
                        queue.append([my,mx])
                        visited[my][mx]=cnt+1
    if visited[gy][gx]==inf:
        print(-1)
    else:
        print(visited[gy][gx])


tate,yoko=map(int,input().split())
sy,sx=map(int,input().split())
gy,gx=map(int,input().split())
sy,sx,gy,gx=sy-1,sx-1,gy-1,gx-1
maze=[]
inf=float('inf')
visited=[[inf]*yoko for i in range(tate)]

for i in range(tate):
    line=list(input())
    maze.append(line)
bfs()




Fixed submission:
from collections import deque
def bfs():
    move=[[1,0],[0,1],[-1,0],[0,-1]]
    
    queue=deque()
    queue.append([sy,sx]) #queue=deque([[sy,sx]])でもよい
    visited[sy][sx]=0 #スタート地点の距離は0
    while queue:
        y,x=queue.popleft()
        cnt=visited[y][x]
        
        for dy,dx in move:
            my,mx=y+dy,x+dx 
            if my<0 or my>=tate:
                continue
            if mx<0 or mx>=yoko:
                continue
            if maze[my][mx]=="#":
                continue
            if visited[my][mx]>cnt:
                queue.appendleft([my,mx])
                visited[my][mx]=cnt # visitedは距離も兼ねてる
        for my in range(y-2,y+3):
            for mx in range(x-2,x+3):
                if my<0 or my>=tate:
                    continue
                if mx<0 or mx>=yoko:
                    continue
                if maze[my][mx]=="#":
                    continue
                if visited[my][mx]>cnt+1:
                    queue.append([my,mx])
                    visited[my][mx]=cnt+1
    if visited[gy][gx]==inf:
        print(-1)
    else:
        print(visited[gy][gx])


tate,yoko=map(int,input().split())
sy,sx=map(int,input().split())
gy,gx=map(int,input().split())
sy,sx,gy,gx=sy-1,sx-1,gy-1,gx-1
maze=[]
inf=float('inf')
visited=[[inf]*yoko for i in range(tate)]

for i in range(tate):
    line=list(input())
    maze.append(line)
bfs()

Buggy python submission (verdict: Time Limit Exceeded):
from collections import deque
def bfs():
    move=[[1,0],[0,1],[-1,0],[0,-1]]
    
    queue=deque()
    queue.append([sy,sx]) #queue=deque([[sy,sx]])でもよい
    visited[sy][sx]=0 #スタート地点の距離は0
    while queue:
        y,x=queue.popleft()
        cnt=visited[y][x]
        
        for dy,dx in move:
            my,mx=y+dy,x+dx 
            if (0<=my<tate and 0<=mx<yoko) and maze[my][mx]=="." and visited[my][mx]>cnt:
                queue.append([my,mx])
                visited[my][mx]=cnt # visitedは距離も兼ねてる
        for my in range(y-2,y+3):
            for mx in range(x-2,x+3):
                if (0<=my<tate and 0<=mx<yoko) and maze[my][mx]==".":
                    if visited[my][mx]>cnt+1:
                        queue.append([my,mx])
                        visited[my][mx]=cnt+1
    if visited[gy][gx]==inf:
        print(-1)
    else:
        print(visited[gy][gx])


tate,yoko=map(int,input().split())
sy,sx=map(int,input().split())
gy,gx=map(int,input().split())
sy,sx,gy,gx=sy-1,sx-1,gy-1,gx-1
maze=[]
inf=float('inf')
visited=[[inf]*yoko for i in range(tate)]

for i in range(tate):
    line=list(input())
    maze.append(line)
bfs()

Fixed submission:
from collections import deque
def bfs():
    move=[[1,0],[0,1],[-1,0],[0,-1]]
    
    queue=deque()
    queue.append([sy,sx]) #queue=deque([[sy,sx]])でもよい
    visited[sy][sx]=0 #スタート地点の距離は0
    while queue:
        y,x=queue.popleft()
        cnt=visited[y][x]
        
        for dy,dx in move:
            my,mx=y+dy,x+dx 
            if my<0 or my>=tate:
                continue
            if mx<0 or mx>=yoko:
                continue
            if maze[my][mx]=="#":
                continue
            if visited[my][mx]>cnt:
                queue.appendleft([my,mx])
                visited[my][mx]=cnt # visitedは距離も兼ねてる
        for my in range(y-2,y+3):
            for mx in range(x-2,x+3):
                if my<0 or my>=tate:
                    continue
                if mx<0 or mx>=yoko:
                    continue
                if maze[my][mx]=="#":
                    continue
                if visited[my][mx]>cnt+1:
                    queue.append([my,mx])
                    visited[my][mx]=cnt+1
    if visited[gy][gx]==inf:
        print(-1)
    else:
        print(visited[gy][gx])


tate,yoko=map(int,input().split())
sy,sx=map(int,input().split())
gy,gx=map(int,input().split())
sy,sx,gy,gx=sy-1,sx-1,gy-1,gx-1
maze=[]
inf=float('inf')
visited=[[inf]*yoko for i in range(tate)]

for i in range(tate):
    line=list(input())
    maze.append(line)
bfs()