Buggy python submission (verdict: Runtime Error):
from collections import deque
H, W = map(int, input().split())
G = [list(input()) for i in range(H)]  # 迷路
D = [[-1] * W for i in range(W)]  # 最短距離
D[0][0] = 0

Black = 0  # 最初の盤面の黒の数
for g in G:
    Black += g.count('#')

# BFS
que = deque([[0, 0]])
direction = [(1, 0), (-1, 0), (0, 1), (0, -1)]
while que:
    nh, nw = que.pop()
    for dh, dw in direction:
        if not 0 <= nh + dh < H:
            continue
        
        if not 0 <= nw + dw < W:
            continue
            
        if D[nh + dh][nw + dw] > 0:
            continue

        if G[nh + dh][nw + dw] == '#':
            continue

        D[nh + dh][nw + dw] = D[nh][nw] + 1
        que.appendleft([nh + dh, nw + dw])

if D[H - 1][W - 1]:
    print(H * W - D[H - 1][W - 1] - Black - 1)
else:
    print(-1)


Fixed submission:
from collections import deque
H, W = map(int, input().split())
Field = [list(input()) for i in range(H)]

que = deque()
que.append([0, 0])
Field[0][0] = 0

while que:
    now = que.popleft()
    if now == [H-1, W-1]:
        break

    if now[0]+1 <= H -1:
        if Field[now[0]+1][now[1]] == ".":
            Field[now[0]+1][now[1]] = str(int(Field[now[0]][now[1]])+1)
            que.append([now[0]+1, now[1]])

    if now[0]-1 >= 0:
        if Field[now[0]-1][now[1]] == ".":
            Field[now[0]-1][now[1]] = str(int(Field[now[0]][now[1]])+1)
            que.append([now[0]-1, now[1]])

    if now[1] + 1 <= W -1:
        if Field[now[0]][now[1]+1] == ".":
            Field[now[0]][now[1]+1] = str(int(Field[now[0]][now[1]])+1)
            que.append([now[0], now[1]+1])

    if now[1] -1 >= 0:
        if Field[now[0]][now[1]-1] == ".":
            Field[now[0]][now[1]-1] = str(int(Field[now[0]][now[1]])+1)
            que.append([now[0], now[1]-1])
else:
    print(-1)
    exit()
Z = int(Field[H-1][W-1])

sharp_cnt = 0
for f in Field:
    sharp_cnt += f.count("#")

print(H*W - sharp_cnt - Z - 1)

Buggy python submission (verdict: Runtime Error):
from collections import deque
H, W = map(int, input().split())
G = [list(input()) for i in range(H)]  # 迷路
D = [[-1] * W for i in range(W)]  # 最短距離
D[0][0] = 0

Black = 0  # 最初の盤面の黒の数
for g in G:
    Black += g.count('#')

# BFS
que = deque([[0, 0]])
direction = [(1, 0), (-1, 0), (0, 1), (0, -1)]
while que:
    nh, nw = que.pop()
    for dh, dw in direction:
        if not ((0 <= nh + dh < H) and (0 <= nw + dw < W)):
            continue

        if D[nh + dh][nw + dw] > 0:
            continue

        if G[nh + dh][nw + dw] == '#':
            continue

        D[nh + dh][nw + dw] = D[nh][nw] + 1
        que.appendleft([nh + dh, nw + dw])

if D[H - 1][W - 1]:
    print(H * W - D[H - 1][W - 1] - Black - 1)
else:
    print(-1)


Fixed submission:
from collections import deque
H, W = map(int, input().split())
Field = [list(input()) for i in range(H)]

que = deque()
que.append([0, 0])
Field[0][0] = 0

while que:
    now = que.popleft()
    if now == [H-1, W-1]:
        break

    if now[0]+1 <= H -1:
        if Field[now[0]+1][now[1]] == ".":
            Field[now[0]+1][now[1]] = str(int(Field[now[0]][now[1]])+1)
            que.append([now[0]+1, now[1]])

    if now[0]-1 >= 0:
        if Field[now[0]-1][now[1]] == ".":
            Field[now[0]-1][now[1]] = str(int(Field[now[0]][now[1]])+1)
            que.append([now[0]-1, now[1]])

    if now[1] + 1 <= W -1:
        if Field[now[0]][now[1]+1] == ".":
            Field[now[0]][now[1]+1] = str(int(Field[now[0]][now[1]])+1)
            que.append([now[0], now[1]+1])

    if now[1] -1 >= 0:
        if Field[now[0]][now[1]-1] == ".":
            Field[now[0]][now[1]-1] = str(int(Field[now[0]][now[1]])+1)
            que.append([now[0], now[1]-1])
else:
    print(-1)
    exit()
Z = int(Field[H-1][W-1])

sharp_cnt = 0
for f in Field:
    sharp_cnt += f.count("#")

print(H*W - sharp_cnt - Z - 1)

Buggy python submission (verdict: Runtime Error):
from collections import deque
H, W = map(int, input().split())
G = [list(input()) for i in range(H)]  # 迷路
D = [[None] * W for i in range(W)]  # 最短距離
D[0][0] = 0

Black = 0  # 最初の盤面の黒の数
for g in G:
    Black += g.count('#')

# BFS
que = deque([[0, 0]])
direction = [(1, 0), (-1, 0), (0, 1), (0, -1)]
while que:
    nh, nw = que.pop()
    for dh, dw in direction:
        if not ((0 <= nh + dh < H) and (0 <= nw + dw < W)):
            continue

        if D[nh + dh][nw + dw] is not None:
            continue

        if G[nh + dh][nw + dw] == '#':
            continue

        D[nh + dh][nw + dw] = D[nh][nw] + 1
        que.appendleft([nh + dh, nw + dw])

if D[H - 1][W - 1]:
    print(H * W - D[H - 1][W - 1] - Black - 1)
else:
    print(-1)


Fixed submission:
from collections import deque
H, W = map(int, input().split())
Field = [list(input()) for i in range(H)]

que = deque()
que.append([0, 0])
Field[0][0] = 0

while que:
    now = que.popleft()
    if now == [H-1, W-1]:
        break

    if now[0]+1 <= H -1:
        if Field[now[0]+1][now[1]] == ".":
            Field[now[0]+1][now[1]] = str(int(Field[now[0]][now[1]])+1)
            que.append([now[0]+1, now[1]])

    if now[0]-1 >= 0:
        if Field[now[0]-1][now[1]] == ".":
            Field[now[0]-1][now[1]] = str(int(Field[now[0]][now[1]])+1)
            que.append([now[0]-1, now[1]])

    if now[1] + 1 <= W -1:
        if Field[now[0]][now[1]+1] == ".":
            Field[now[0]][now[1]+1] = str(int(Field[now[0]][now[1]])+1)
            que.append([now[0], now[1]+1])

    if now[1] -1 >= 0:
        if Field[now[0]][now[1]-1] == ".":
            Field[now[0]][now[1]-1] = str(int(Field[now[0]][now[1]])+1)
            que.append([now[0], now[1]-1])
else:
    print(-1)
    exit()
Z = int(Field[H-1][W-1])

sharp_cnt = 0
for f in Field:
    sharp_cnt += f.count("#")

print(H*W - sharp_cnt - Z - 1)

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

black = 0
for g in G:
    black += g.count("#")


que = deque()
que.append([0, 0, 0])
direction = [(0, 1), (0, -1), (1, 0), (-1, 0)]

while que:
    nh, nw, cost = que.pop()
    G[nh][nw] = cost
    if G[H - 1][W - 1] != ".":
        print(H * W - black - int(G[H - 1][W - 1]) - 1)
        break

    for dh, dw in direction:
        if (0 <= nh + dh < H) & (0 <= nw + dw < W):
            if G[nh + dh][nw + dw] == ".":
                que.appendleft((nh + dh, nw + dw, cost + 1))
else:
    print(-1)


Fixed submission:
from collections import deque
H, W = map(int, input().split())
Field = [list(input()) for i in range(H)]

que = deque()
que.append([0, 0])
Field[0][0] = 0

while que:
    now = que.popleft()
    if now == [H-1, W-1]:
        break

    if now[0]+1 <= H -1:
        if Field[now[0]+1][now[1]] == ".":
            Field[now[0]+1][now[1]] = str(int(Field[now[0]][now[1]])+1)
            que.append([now[0]+1, now[1]])

    if now[0]-1 >= 0:
        if Field[now[0]-1][now[1]] == ".":
            Field[now[0]-1][now[1]] = str(int(Field[now[0]][now[1]])+1)
            que.append([now[0]-1, now[1]])

    if now[1] + 1 <= W -1:
        if Field[now[0]][now[1]+1] == ".":
            Field[now[0]][now[1]+1] = str(int(Field[now[0]][now[1]])+1)
            que.append([now[0], now[1]+1])

    if now[1] -1 >= 0:
        if Field[now[0]][now[1]-1] == ".":
            Field[now[0]][now[1]-1] = str(int(Field[now[0]][now[1]])+1)
            que.append([now[0], now[1]-1])
else:
    print(-1)
    exit()
Z = int(Field[H-1][W-1])

sharp_cnt = 0
for f in Field:
    sharp_cnt += f.count("#")

print(H*W - sharp_cnt - Z - 1)

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

black = 0
for g in G:
    black += g.count("#")


que = deque()
que.append([0, 0, 0])
direction = [(0, 1), (0, -1), (1, 0), (-1, 0)]

while que:
    nh, nw, cost = que.pop()
    G[nh][nw] = cost
    if (nh == H - 1) & (nw == W - 1):
        print(H * W - black - int(G[H - 1][W - 1]) - 1)
        break

    for dh, dw in direction:
        if (0 <= nh + dh < H) & (0 <= nw + dw < W):
            if G[nh + dh][nw + dw] == ".":
                que.appendleft((nh + dh, nw + dw, cost + 1))
else:
    print(-1)


Fixed submission:
from collections import deque
H, W = map(int, input().split())
Field = [list(input()) for i in range(H)]

que = deque()
que.append([0, 0])
Field[0][0] = 0

while que:
    now = que.popleft()
    if now == [H-1, W-1]:
        break

    if now[0]+1 <= H -1:
        if Field[now[0]+1][now[1]] == ".":
            Field[now[0]+1][now[1]] = str(int(Field[now[0]][now[1]])+1)
            que.append([now[0]+1, now[1]])

    if now[0]-1 >= 0:
        if Field[now[0]-1][now[1]] == ".":
            Field[now[0]-1][now[1]] = str(int(Field[now[0]][now[1]])+1)
            que.append([now[0]-1, now[1]])

    if now[1] + 1 <= W -1:
        if Field[now[0]][now[1]+1] == ".":
            Field[now[0]][now[1]+1] = str(int(Field[now[0]][now[1]])+1)
            que.append([now[0], now[1]+1])

    if now[1] -1 >= 0:
        if Field[now[0]][now[1]-1] == ".":
            Field[now[0]][now[1]-1] = str(int(Field[now[0]][now[1]])+1)
            que.append([now[0], now[1]-1])
else:
    print(-1)
    exit()
Z = int(Field[H-1][W-1])

sharp_cnt = 0
for f in Field:
    sharp_cnt += f.count("#")

print(H*W - sharp_cnt - Z - 1)

Buggy python submission (verdict: Runtime Error):
from collections import deque
H, W = map(int, input().split())
G = [list(input()) for i in range(H)]

black = 0
for g in G:
    black += g.count("#")


que = deque()
que.append([0, 0, 0])
direction = [(0, 1), (0, -1), (1, 0), (-1, 0)]

while que:
    nh, nw, cost = que.pop()
    G[nh][nw] = cost
    if nh == H - 1 & nw == W - 1:
        break

    for dh, dw in direction:
        if (0 <= nh + dh < H) & (0 <= nw + dw < W):
            if G[nh + dh][nw + dw] == ".":
                que.appendleft((nh + dh, nw + dw, cost + 1))

print(H * W - black - int(G[H - 1][W - 1]) - 1)


Fixed submission:
from collections import deque
H, W = map(int, input().split())
Field = [list(input()) for i in range(H)]

que = deque()
que.append([0, 0])
Field[0][0] = 0

while que:
    now = que.popleft()
    if now == [H-1, W-1]:
        break

    if now[0]+1 <= H -1:
        if Field[now[0]+1][now[1]] == ".":
            Field[now[0]+1][now[1]] = str(int(Field[now[0]][now[1]])+1)
            que.append([now[0]+1, now[1]])

    if now[0]-1 >= 0:
        if Field[now[0]-1][now[1]] == ".":
            Field[now[0]-1][now[1]] = str(int(Field[now[0]][now[1]])+1)
            que.append([now[0]-1, now[1]])

    if now[1] + 1 <= W -1:
        if Field[now[0]][now[1]+1] == ".":
            Field[now[0]][now[1]+1] = str(int(Field[now[0]][now[1]])+1)
            que.append([now[0], now[1]+1])

    if now[1] -1 >= 0:
        if Field[now[0]][now[1]-1] == ".":
            Field[now[0]][now[1]-1] = str(int(Field[now[0]][now[1]])+1)
            que.append([now[0], now[1]-1])
else:
    print(-1)
    exit()
Z = int(Field[H-1][W-1])

sharp_cnt = 0
for f in Field:
    sharp_cnt += f.count("#")

print(H*W - sharp_cnt - Z - 1)

Buggy python submission (verdict: Runtime Error):
from collections import deque
H, W = map(int, input().split())
Field = [list(input()) for i in range(H)]

que = deque()
que.append([0, 0])
Field[0][0] = 0

while que:
    now = que.popleft()
    if now == [H-1, W-1]:
        break

    if now[0]+1 <= H -1:
        if Field[now[0]+1][now[1]] == ".":
            Field[now[0]+1][now[1]] = str(int(Field[now[0]][now[1]])+1)
            que.append([now[0]+1, now[1]])

    if now[0]-1 >= 0:
        if Field[now[0]-1][now[1]] == ".":
            Field[now[0]-1][now[1]] = str(int(Field[now[0]][now[1]])+1)
            que.append([now[0]-1, now[1]])

    if now[1] + 1 <= W -1:
        if Field[now[0]][now[1]+1] == ".":
            Field[now[0]][now[1]+1] = str(int(Field[now[0]][now[1]])+1)
            que.append([now[0], now[1]+1])

    if now[1] -1 >= 0:
        if Field[now[0]][now[1]-1] == ".":
            Field[now[0]][now[1]-1] = str(int(Field[now[0]][now[1]])+1)
            que.append([now[0], now[1]-1])

Z = int(Field[H-1][W-1])

sharp_cnt = 0
for f in Field:
    sharp_cnt += f.count("#")

print(H*W - sharp_cnt - Z - 1)


Fixed submission:
from collections import deque
H, W = map(int, input().split())
Field = [list(input()) for i in range(H)]

que = deque()
que.append([0, 0])
Field[0][0] = 0

while que:
    now = que.popleft()
    if now == [H-1, W-1]:
        break

    if now[0]+1 <= H -1:
        if Field[now[0]+1][now[1]] == ".":
            Field[now[0]+1][now[1]] = str(int(Field[now[0]][now[1]])+1)
            que.append([now[0]+1, now[1]])

    if now[0]-1 >= 0:
        if Field[now[0]-1][now[1]] == ".":
            Field[now[0]-1][now[1]] = str(int(Field[now[0]][now[1]])+1)
            que.append([now[0]-1, now[1]])

    if now[1] + 1 <= W -1:
        if Field[now[0]][now[1]+1] == ".":
            Field[now[0]][now[1]+1] = str(int(Field[now[0]][now[1]])+1)
            que.append([now[0], now[1]+1])

    if now[1] -1 >= 0:
        if Field[now[0]][now[1]-1] == ".":
            Field[now[0]][now[1]-1] = str(int(Field[now[0]][now[1]])+1)
            que.append([now[0], now[1]-1])
else:
    print(-1)
    exit()
Z = int(Field[H-1][W-1])

sharp_cnt = 0
for f in Field:
    sharp_cnt += f.count("#")

print(H*W - sharp_cnt - Z - 1)