Buggy python submission (verdict: Time Limit Exceeded):
from collections import deque
H,W=map(int,input().split())
white=0
s=[]
for y in range(H):
    line=input()
    white+=line.count('.')
    s.append(list(line))

q = deque([(0,0,1)])
q_append=q.append
q_popleft=q.popleft
while q:
    x,y,l=q_popleft()
    if x==W-1 and y==H-1:
        print(white-l)
        break
    s[y][x]='*'
    for d in [(1,0),(0,1),(-1,0),(0,-1)]:
        nx, ny=(x+d[0],y+d[1])
        if 0<=nx<W and 0<=ny<H and s[ny][nx]=='.':
            q_append((nx,ny,l+1))
else:
    print(-1)
    


Fixed submission:
from collections import deque
H,W=map(int,input().split())
white=0
s=[]
for y in range(H):
    line=input()
    white+=line.count('.')
    s.append(list(line))

q = deque([(0,0,1)])
q_append=q.append
q_popleft=q.popleft
while q:
    x,y,l=q_popleft()
    if s[y][x]!='.':
        continue
    if x==W-1 and y==H-1:
        print(white-l)
        break
    s[y][x]='*'
    for d in [(1,0),(0,1),(-1,0),(0,-1)]:
        nx, ny=(x+d[0],y+d[1])
        if 0<=nx<W and 0<=ny<H:
            q_append((nx,ny,l+1))
else:
    print(-1)

Buggy python submission (verdict: Time Limit Exceeded):
from collections import deque
H,W=map(int,input().split())
white=0
s=[]
for y in range(H):
    line=input()
    white+=line.count('.')
    s.append(list(line))

q = deque([(0,0,1)])
while q:
    x,y,l=q.popleft()
    if x==W-1 and y==H-1:
        print(white-l)
        break
    s[y][x]='*'
    for d in [(1,0),(0,1),(-1,0),(0,-1)]:
        nx, ny=(x+d[0],y+d[1])
        if 0<=nx<W and 0<=ny<H and s[ny][nx]=='.':
            q.append((nx,ny,l+1))
else:
    print(-1)
    


Fixed submission:
from collections import deque
H,W=map(int,input().split())
white=0
s=[]
for y in range(H):
    line=input()
    white+=line.count('.')
    s.append(list(line))

q = deque([(0,0,1)])
q_append=q.append
q_popleft=q.popleft
while q:
    x,y,l=q_popleft()
    if s[y][x]!='.':
        continue
    if x==W-1 and y==H-1:
        print(white-l)
        break
    s[y][x]='*'
    for d in [(1,0),(0,1),(-1,0),(0,-1)]:
        nx, ny=(x+d[0],y+d[1])
        if 0<=nx<W and 0<=ny<H:
            q_append((nx,ny,l+1))
else:
    print(-1)

Buggy python submission (verdict: Time Limit Exceeded):
from collections import deque
H,W=map(int,input().split())
s=[list(input()) for _ in range(H)]

white=sum([1 if s[y][x]=='.' else 0 for x in range(W) for y in range(H)])
q = deque([(0,0,1)])
while q:
    x,y,l=q.popleft()
    if x==W-1 and y==H-1:
        print(white-l)
        break
    s[y][x]='*'
    for d in [(1,0),(0,1),(-1,0),(0,-1)]:
        nx, ny=(x+d[0],y+d[1])
        if 0<=nx<W and 0<=ny<H and s[ny][nx]=='.':
            q.append((nx,ny,l+1))
else:
    print(-1)
    


Fixed submission:
from collections import deque
H,W=map(int,input().split())
white=0
s=[]
for y in range(H):
    line=input()
    white+=line.count('.')
    s.append(list(line))

q = deque([(0,0,1)])
q_append=q.append
q_popleft=q.popleft
while q:
    x,y,l=q_popleft()
    if s[y][x]!='.':
        continue
    if x==W-1 and y==H-1:
        print(white-l)
        break
    s[y][x]='*'
    for d in [(1,0),(0,1),(-1,0),(0,-1)]:
        nx, ny=(x+d[0],y+d[1])
        if 0<=nx<W and 0<=ny<H:
            q_append((nx,ny,l+1))
else:
    print(-1)

Buggy python submission (verdict: Time Limit Exceeded):
from collections import deque
H,W=map(int,input().split())
s=[list(input()) for _ in range(H)]

white=sum([1 if s[y][x]=='.' else 0 for x in range(W) for y in range(H)])
used=[[False for x in range(W)] for y in range(H)]
q = deque([(0,0,1)])
while True:
    if len(q)==0:
        print(-1)
        break
    x,y,l=q.popleft()
    if x==W-1 and y==H-1:
        print(white-l)
        break
    used[y][x]=True
    for d in [(1,0),(0,1),(-1,0),(0,-1)]:
        nx=x+d[0]
        ny=y+d[1]
        if ny>=0 and ny<H and nx>=0 and nx<W and not used[ny][nx]:
            if s[ny][nx]=='.':
                q.append((nx,ny,l+1))
    


Fixed submission:
from collections import deque
H,W=map(int,input().split())
white=0
s=[]
for y in range(H):
    line=input()
    white+=line.count('.')
    s.append(list(line))

q = deque([(0,0,1)])
q_append=q.append
q_popleft=q.popleft
while q:
    x,y,l=q_popleft()
    if s[y][x]!='.':
        continue
    if x==W-1 and y==H-1:
        print(white-l)
        break
    s[y][x]='*'
    for d in [(1,0),(0,1),(-1,0),(0,-1)]:
        nx, ny=(x+d[0],y+d[1])
        if 0<=nx<W and 0<=ny<H:
            q_append((nx,ny,l+1))
else:
    print(-1)

Buggy python submission (verdict: Time Limit Exceeded):
from queue import Queue
H,W=map(int,input().split())
s=[list(input()) for _ in range(H)]

white=sum([1 if s[y][x]=='.' else 0 for x in range(W) for y in range(H)])
used=[[False for x in range(W)] for y in range(H)]
q=Queue()
q.put((0,0,1))
while True:
    if q.empty():
        print(-1)
        break
    x,y,l=q.get()
    if x==W-1 and y==H-1:
        print(white-l)
        break
    used[y][x]=True
    for d in [(1,0),(0,1),(-1,0),(0,-1)]:
        nx=x+d[0]
        ny=y+d[1]
        if ny>=0 and ny<H and nx>=0 and nx<W and not used[ny][nx]:
            if s[ny][nx]=='.':
                q.put((nx,ny,l+1))
    


Fixed submission:
from collections import deque
H,W=map(int,input().split())
white=0
s=[]
for y in range(H):
    line=input()
    white+=line.count('.')
    s.append(list(line))

q = deque([(0,0,1)])
q_append=q.append
q_popleft=q.popleft
while q:
    x,y,l=q_popleft()
    if s[y][x]!='.':
        continue
    if x==W-1 and y==H-1:
        print(white-l)
        break
    s[y][x]='*'
    for d in [(1,0),(0,1),(-1,0),(0,-1)]:
        nx, ny=(x+d[0],y+d[1])
        if 0<=nx<W and 0<=ny<H:
            q_append((nx,ny,l+1))
else:
    print(-1)

Buggy python submission (verdict: Time Limit Exceeded):
from queue import Queue
H,W=map(int,input().split())
s=[list(input()) for _ in range(H)]

white=sum([1 if s[y][x]=='.' else 0 for x in range(W) for y in range(H)])
used=[[False for x in range(W)] for y in range(H)]
q=Queue()
q.put((0,0,1))
while True:
    if q.empty():
        print(-1)
        break
    x,y,l=q.get()
    if x==W-1 and y==H-1:
        print(white-l)
        break
    used[y][x]=True
    for d in [(1,0),(0,1),(-1,0),(0,-1)]:
        nx=x+d[0]
        ny=y+d[1]
        if ny>=0 and ny<H and nx>=0 and nx<W and not used[ny][nx]:
            if s[ny][nx]=='.':
                q.put((nx,ny,l+1))
    


Fixed submission:
from collections import deque
H,W=map(int,input().split())
white=0
s=[]
for y in range(H):
    line=input()
    white+=line.count('.')
    s.append(list(line))

q = deque([(0,0,1)])
q_append=q.append
q_popleft=q.popleft
while q:
    x,y,l=q_popleft()
    if s[y][x]!='.':
        continue
    if x==W-1 and y==H-1:
        print(white-l)
        break
    s[y][x]='*'
    for d in [(1,0),(0,1),(-1,0),(0,-1)]:
        nx, ny=(x+d[0],y+d[1])
        if 0<=nx<W and 0<=ny<H:
            q_append((nx,ny,l+1))
else:
    print(-1)