Buggy python submission (verdict: Runtime Error):
import numpy as np

h , w = map(int, input().split())
visited = np.zeros((h,w))

for y in range(h):
    _in = input()
    for x, value in enumerate(_in):
        if value == '.':
            visited[y][x] = 10**9
for i in range(1,h):
    visited[i,:] = np.minimum(visited[i,:],visited[i-1,:]+1)
for i in reversed(range(h-1)):
    visited[i,:] = np.minimum(visited[i,:],visited[i+1,:]+1)
for j in range(1,h):
    visited[:,j] = np.minimum(visited[:,j],visited[:,j-1]+1)
for j in reversed(range(h-1)):
    visited[:,j] = np.minimum(visited[:,j],visited[:,j+1]+1)
print(np.max(visited))

Fixed submission:
from collections import deque
 
 
def dfs(field):
    q = deque([(0, 0, 0)])
    visited = [[False] * w for _ in range(h)]
    while q:
        i, j, d = q.popleft()
        if i == h - 1 and j == w - 1:
            return d
        if visited[i][j]:
            continue
        visited[i][j] = True
        if i > 0 and field[i - 1][j] == '.':
            q.append((i - 1, j, d + 1))
        if i < h - 1 and field[i + 1][j] == '.':
            q.append((i + 1, j, d + 1))
        if j > 0 and field[i][j - 1] == '.':
            q.append((i, j - 1, d + 1))
        if j < w - 1 and field[i][j + 1] == '.':
            q.append((i, j + 1, d + 1))
    else:
        return -1
 
 
h, w = map(int, input().split())
field = [input() for _ in range(h)]
dot_cnt = sum(r.count('.') for r in field)
d = dfs(field)
if d == -1:
    print(-1)
else:
    print(dot_cnt - (d+1))

Buggy python submission (verdict: Runtime Error):
from collections import deque
import sys

def my_bfs(field, R, C):
    sy, sx = 1, 1
    gy, gx = R, C
    dxy = [(0,1), (0,-1), (1,0), (-1,0)]
    flg = False
    cnt = 0
    dot_num = sum(r.count('.') for r in field)

    q = deque()
    q.append([sy, sx])
    field[sy][sx] = 0
    while flg == False:
        yx = q.popleft()
        cnt = field[yx[0]][yx[1]]
        for dy, dx in dxy:
            y_n, x_n = yx[0] + dy, yx[1] + dx
            if y_n == gy and x_n == gx:
                field[y_n][x_n] = cnt + 1
                flg = True
                return(dot_num - (cnt+2))
                break
            if field[y_n][x_n] == '#':
                continue
            if field[y_n][x_n] == '.':
                q.append([y_n, x_n])
                field[y_n][x_n] = cnt + 1
        if flg:
            break
    else:
        return(-1)

sys.setrecursionlimit(10**6)

R, C = map(int, input().split())
field = [["#"] * (C + 2)] + \
        [list("#" + input() + "#") for i in range(R)] + \
        [["#"] * (C + 2)]

out = my_bfs(field, R, C)
print(out)

Fixed submission:
from collections import deque
 
 
def dfs(field):
    q = deque([(0, 0, 0)])
    visited = [[False] * w for _ in range(h)]
    while q:
        i, j, d = q.popleft()
        if i == h - 1 and j == w - 1:
            return d
        if visited[i][j]:
            continue
        visited[i][j] = True
        if i > 0 and field[i - 1][j] == '.':
            q.append((i - 1, j, d + 1))
        if i < h - 1 and field[i + 1][j] == '.':
            q.append((i + 1, j, d + 1))
        if j > 0 and field[i][j - 1] == '.':
            q.append((i, j - 1, d + 1))
        if j < w - 1 and field[i][j + 1] == '.':
            q.append((i, j + 1, d + 1))
    else:
        return -1
 
 
h, w = map(int, input().split())
field = [input() for _ in range(h)]
dot_cnt = sum(r.count('.') for r in field)
d = dfs(field)
if d == -1:
    print(-1)
else:
    print(dot_cnt - (d+1))

Buggy python submission (verdict: Runtime Error):
from collections import deque
import sys

sys.setrecursionlimit(10**6)

R, C = map(int, input().split())
sy, sx = 1, 1
gy, gx = R, C

field = [["#"] * (C + 2)] + \
        [list("#" + input() + "#") for i in range(R)] + \
        [["#"] * (C + 2)]
dxy = [(0,1), (0,-1), (1,0), (-1,0)]
flg = False
cnt = 0

dot_num = sum(r.count('.') for r in field)

q = deque()
q.append([sy, sx])
field[sy][sx] = 0

while flg == False:
    yx = q.popleft()
    cnt = field[yx[0]][yx[1]]
    for dy, dx in dxy:
        y_n, x_n = yx[0] + dy, yx[1] + dx
        if y_n == gy and x_n == gx:
            field[y_n][x_n] = cnt + 1
            flg = True
            print(dot_num - (cnt+2))
            break
        if field[y_n][x_n] == '#':
            continue
        if field[y_n][x_n] == '.':
            q.append([y_n, x_n])
            field[y_n][x_n] = cnt + 1
    if flg:
        break
if flg == False:
    print(-1)

Fixed submission:
from collections import deque
 
 
def dfs(field):
    q = deque([(0, 0, 0)])
    visited = [[False] * w for _ in range(h)]
    while q:
        i, j, d = q.popleft()
        if i == h - 1 and j == w - 1:
            return d
        if visited[i][j]:
            continue
        visited[i][j] = True
        if i > 0 and field[i - 1][j] == '.':
            q.append((i - 1, j, d + 1))
        if i < h - 1 and field[i + 1][j] == '.':
            q.append((i + 1, j, d + 1))
        if j > 0 and field[i][j - 1] == '.':
            q.append((i, j - 1, d + 1))
        if j < w - 1 and field[i][j + 1] == '.':
            q.append((i, j + 1, d + 1))
    else:
        return -1
 
 
h, w = map(int, input().split())
field = [input() for _ in range(h)]
dot_cnt = sum(r.count('.') for r in field)
d = dfs(field)
if d == -1:
    print(-1)
else:
    print(dot_cnt - (d+1))

Buggy python submission (verdict: Runtime Error):
from collections import deque

R, C = map(int, input().split())
sy, sx = 1, 1
gy, gx = R, C

field = [["#"] * (C + 2)] + \
        [list("#" + input() + "#") for i in range(R)] + \
        [["#"] * (C + 2)]
dxy = [(0,1), (0,-1), (1,0), (-1,0)]
flg = False
cnt = 0

dot_num = sum(r.count('.') for r in field)

q = deque()
q.append([sy, sx])
field[sy][sx] = 0

while flg == False:
    yx = q.popleft()
    cnt = field[yx[0]][yx[1]]
    for dy, dx in dxy:
        y_n, x_n = yx[0] + dy, yx[1] + dx
        if y_n == gy and x_n == gx:
            field[y_n][x_n] = cnt + 1
            flg = True
            print(dot_num - (cnt+2))
            break
        if field[y_n][x_n] == '#':
            continue
        if field[y_n][x_n] == '.':
            q.append([y_n, x_n])
            field[y_n][x_n] = cnt + 1
    if flg:
        break
if flg == False:
    print(-1)

Fixed submission:
from collections import deque
 
 
def dfs(field):
    q = deque([(0, 0, 0)])
    visited = [[False] * w for _ in range(h)]
    while q:
        i, j, d = q.popleft()
        if i == h - 1 and j == w - 1:
            return d
        if visited[i][j]:
            continue
        visited[i][j] = True
        if i > 0 and field[i - 1][j] == '.':
            q.append((i - 1, j, d + 1))
        if i < h - 1 and field[i + 1][j] == '.':
            q.append((i + 1, j, d + 1))
        if j > 0 and field[i][j - 1] == '.':
            q.append((i, j - 1, d + 1))
        if j < w - 1 and field[i][j + 1] == '.':
            q.append((i, j + 1, d + 1))
    else:
        return -1
 
 
h, w = map(int, input().split())
field = [input() for _ in range(h)]
dot_cnt = sum(r.count('.') for r in field)
d = dfs(field)
if d == -1:
    print(-1)
else:
    print(dot_cnt - (d+1))

Buggy python submission (verdict: Time Limit Exceeded):
from queue import Queue

R, C = map(int, input().split())
sy, sx = 1, 1
gy, gx = R, C

field = [["#"] * (C + 2)] + \
        [list("#" + input() + "#") for i in range(R)] + \
        [["#"] * (C + 2)]
dxy = [(0,1), (0,-1), (1,0), (-1,0)]
flg = False
cnt = 0

dot_num = sum(r.count('.') for r in field)

q = Queue()
q.put([sy, sx])
field[sy][sx] = 0

while flg == False:
    yx = q.get()
    cnt = field[yx[0]][yx[1]]
    for dy, dx in dxy:
        y_n, x_n = yx[0] + dy, yx[1] + dx
        if y_n == gy and x_n == gx:
            field[y_n][x_n] = cnt + 1
            flg = True
            print(dot_num - (cnt+2))
            break
        if field[y_n][x_n] == '#':
            continue
        if field[y_n][x_n] == '.':
            q.put([y_n, x_n])
            field[y_n][x_n] = cnt + 1
    if flg:
        break
if flg == False:
    print(-1)

Fixed submission:
from collections import deque
 
 
def dfs(field):
    q = deque([(0, 0, 0)])
    visited = [[False] * w for _ in range(h)]
    while q:
        i, j, d = q.popleft()
        if i == h - 1 and j == w - 1:
            return d
        if visited[i][j]:
            continue
        visited[i][j] = True
        if i > 0 and field[i - 1][j] == '.':
            q.append((i - 1, j, d + 1))
        if i < h - 1 and field[i + 1][j] == '.':
            q.append((i + 1, j, d + 1))
        if j > 0 and field[i][j - 1] == '.':
            q.append((i, j - 1, d + 1))
        if j < w - 1 and field[i][j + 1] == '.':
            q.append((i, j + 1, d + 1))
    else:
        return -1
 
 
h, w = map(int, input().split())
field = [input() for _ in range(h)]
dot_cnt = sum(r.count('.') for r in field)
d = dfs(field)
if d == -1:
    print(-1)
else:
    print(dot_cnt - (d+1))

Buggy python submission (verdict: Runtime Error):
from collections import deque
import itertools
import numpy as np

R, C = map(int, input().split())
sy, sx = 1, 1
gy, gx = R, C

field = [["#"] * (C + 2)] + \
        [list("#" + input() + "#") for i in range(R)] + \
        [["#"] * (C + 2)]
dxy = [(0,1), (0,-1), (1,0), (-1,0)]
flg = False
cnt = 0

field_1d = list(itertools.chain.from_iterable(field))
field01 = [1 if i == '.' else 0 for i in field_1d]
dot_num = np.array(field01).sum()

q = deque()
q.append([sy, sx])
field[sy][sx] = 0

while flg == False:
    yx = q.popleft()
    cnt = field[yx[0]][yx[1]]
    for dy, dx in dxy:
        y_n, x_n = yx[0] + dy, yx[1] + dx
        if y_n == gy and x_n == gx:
            field[y_n][x_n] = cnt + 1
            flg = True
            print(dot_num - (cnt+2))
            break
        if field[y_n][x_n] == '#':
            continue
        if field[y_n][x_n] == '.':
            q.append([y_n, x_n])
            field[y_n][x_n] = cnt + 1
    if flg:
        break
if flg == False:
    print(-1)

Fixed submission:
from collections import deque
 
 
def dfs(field):
    q = deque([(0, 0, 0)])
    visited = [[False] * w for _ in range(h)]
    while q:
        i, j, d = q.popleft()
        if i == h - 1 and j == w - 1:
            return d
        if visited[i][j]:
            continue
        visited[i][j] = True
        if i > 0 and field[i - 1][j] == '.':
            q.append((i - 1, j, d + 1))
        if i < h - 1 and field[i + 1][j] == '.':
            q.append((i + 1, j, d + 1))
        if j > 0 and field[i][j - 1] == '.':
            q.append((i, j - 1, d + 1))
        if j < w - 1 and field[i][j + 1] == '.':
            q.append((i, j + 1, d + 1))
    else:
        return -1
 
 
h, w = map(int, input().split())
field = [input() for _ in range(h)]
dot_cnt = sum(r.count('.') for r in field)
d = dfs(field)
if d == -1:
    print(-1)
else:
    print(dot_cnt - (d+1))

Buggy python submission (verdict: Runtime Error):
from queue import Queue
import itertools
import numpy as np

R, C = map(int, input().split())
sy, sx = 1, 1
gy, gx = R, C

field = [["#"] * (C + 2)] + \
        [list("#" + input() + "#") for i in range(R)] + \
        [["#"] * (C + 2)]
dxy = [(0,1), (0,-1), (1,0), (-1,0)]
flg = False
cnt = 0

field_1d = list(itertools.chain.from_iterable(field))
field01 = [1 if i == '.' else 0 for i in field_1d]
dot_num = np.array(field01).sum()

q = Queue()
q.put([sy, sx])
field[sy][sx] = 0

while flg == False:
    yx = q.get()
    cnt = field[yx[0]][yx[1]]
    for dy, dx in dxy:
        y_n, x_n = yx[0] + dy, yx[1] + dx
        if y_n == gy and x_n == gx:
            field[y_n][x_n] = cnt + 1
            flg = True
            print(dot_num - (cnt+2))
            break
        if field[y_n][x_n] == '#':
            continue
        if field[y_n][x_n] == '.':
            q.put([y_n, x_n])
            field[y_n][x_n] = cnt + 1
    if flg:
        break
if flg == False:
    print(-1)

Fixed submission:
from collections import deque
 
 
def dfs(field):
    q = deque([(0, 0, 0)])
    visited = [[False] * w for _ in range(h)]
    while q:
        i, j, d = q.popleft()
        if i == h - 1 and j == w - 1:
            return d
        if visited[i][j]:
            continue
        visited[i][j] = True
        if i > 0 and field[i - 1][j] == '.':
            q.append((i - 1, j, d + 1))
        if i < h - 1 and field[i + 1][j] == '.':
            q.append((i + 1, j, d + 1))
        if j > 0 and field[i][j - 1] == '.':
            q.append((i, j - 1, d + 1))
        if j < w - 1 and field[i][j + 1] == '.':
            q.append((i, j + 1, d + 1))
    else:
        return -1
 
 
h, w = map(int, input().split())
field = [input() for _ in range(h)]
dot_cnt = sum(r.count('.') for r in field)
d = dfs(field)
if d == -1:
    print(-1)
else:
    print(dot_cnt - (d+1))

Buggy python submission (verdict: Time Limit Exceeded):
from queue import Queue
import itertools
import numpy as np

R, C = map(int, input().split())
sy, sx = 1, 1
gy, gx = R, C

field = [["#"] * (C + 2)] + \
        [list("#" + input() + "#") for i in range(R)] + \
        [["#"] * (C + 2)]
dxy = [(0,1), (0,-1), (1,0), (-1,0)]
flg = False
cnt = 0

field_1d = list(itertools.chain.from_iterable(field))
field01 = [1 if i == '.' else 0 for i in field_1d]
dot_num = np.array(field01).sum()

q = Queue()
q.put([sy, sx])
field[sy][sx] = 0

while flg == False:
    yx = q.get()
    cnt = field[yx[0]][yx[1]]
    for dy, dx in dxy:
        y_n, x_n = yx[0] + dy, yx[1] + dx
        if y_n == gy and x_n == gx:
            field[y_n][x_n] = cnt + 1
            flg = True
            print(dot_num - (cnt+2))
            break
        if field[y_n][x_n] == '#':
            continue
        if field[y_n][x_n] == '.':
            q.put([y_n, x_n])
            field[y_n][x_n] = cnt + 1
    if flg:
        break
if flg == False:
    print(-1)

Fixed submission:
from collections import deque
 
 
def dfs(field):
    q = deque([(0, 0, 0)])
    visited = [[False] * w for _ in range(h)]
    while q:
        i, j, d = q.popleft()
        if i == h - 1 and j == w - 1:
            return d
        if visited[i][j]:
            continue
        visited[i][j] = True
        if i > 0 and field[i - 1][j] == '.':
            q.append((i - 1, j, d + 1))
        if i < h - 1 and field[i + 1][j] == '.':
            q.append((i + 1, j, d + 1))
        if j > 0 and field[i][j - 1] == '.':
            q.append((i, j - 1, d + 1))
        if j < w - 1 and field[i][j + 1] == '.':
            q.append((i, j + 1, d + 1))
    else:
        return -1
 
 
h, w = map(int, input().split())
field = [input() for _ in range(h)]
dot_cnt = sum(r.count('.') for r in field)
d = dfs(field)
if d == -1:
    print(-1)
else:
    print(dot_cnt - (d+1))

Buggy python submission (verdict: Runtime Error):
from queue import Queue
import itertools
import numpy as np

R, C = map(int, input().split())
sy, sx = 1, 1
gy, gx = R, C

field = [["#"] * (C + 2)] + \
        [list("#" + input() + "#") for i in range(R)] + \
        [["#"] * (C + 2)]
field = np.array(field)
dxy = [(0,1), (0,-1), (1,0), (-1,0)]
flg = False
cnt = 0

field_1d = list(itertools.chain.from_iterable(field))
field01 = [1 if i == '.' else 0 for i in field_1d]
dot_num = np.array(field01).sum()

q = Queue()
q.put([sy, sx])
field[sy][sx] = 0

while flg == False:
    yx = q.get()
    cnt = field[yx[0]][yx[1]]
    for dy, dx in dxy:
        y_n, x_n = yx[0] + dy, yx[1] + dx
        if y_n == gy and x_n == gx:
            field[y_n][x_n] = cnt + 1
            flg = True
            print(dot_num - (cnt+2))
        if field[y_n][x_n] == '#':
            continue
        if field[y_n][x_n] == '.':
            q.put([y_n, x_n])
            field[y_n][x_n] = cnt + 1
if flg == False:
    print(-1)

Fixed submission:
from collections import deque
 
 
def dfs(field):
    q = deque([(0, 0, 0)])
    visited = [[False] * w for _ in range(h)]
    while q:
        i, j, d = q.popleft()
        if i == h - 1 and j == w - 1:
            return d
        if visited[i][j]:
            continue
        visited[i][j] = True
        if i > 0 and field[i - 1][j] == '.':
            q.append((i - 1, j, d + 1))
        if i < h - 1 and field[i + 1][j] == '.':
            q.append((i + 1, j, d + 1))
        if j > 0 and field[i][j - 1] == '.':
            q.append((i, j - 1, d + 1))
        if j < w - 1 and field[i][j + 1] == '.':
            q.append((i, j + 1, d + 1))
    else:
        return -1
 
 
h, w = map(int, input().split())
field = [input() for _ in range(h)]
dot_cnt = sum(r.count('.') for r in field)
d = dfs(field)
if d == -1:
    print(-1)
else:
    print(dot_cnt - (d+1))

Buggy python submission (verdict: Time Limit Exceeded):
from queue import Queue
import itertools
import numpy as np

R, C = map(int, input().split())
sy, sx = 1, 1
gy, gx = R, C

field = [["#"] * (C + 2)] + \
        [list("#" + input() + "#") for i in range(R)] + \
        [["#"] * (C + 2)]
dxy = [(0,1), (1,0), (0,-1), (-1,0)]
flg = False
cnt = 0

field_1d = list(itertools.chain.from_iterable(field))
field01 = [1 if i == '.' else 0 for i in field_1d]
dot_num = np.array(field01).sum()

q = Queue()
q.put([sy, sx])
field[sy][sx] = 0

while flg == False:
    yx = q.get()
    cnt = field[yx[0]][yx[1]]
    for dy, dx in dxy:
        y_n, x_n = yx[0] + dy, yx[1] + dx
        if y_n == gy and x_n == gx:
            field[y_n][x_n] = cnt + 1
            flg = True
            print(dot_num - (cnt+2))
        if field[y_n][x_n] == '#':
            continue
        if field[y_n][x_n] == '.':
            q.put([y_n, x_n])
            field[y_n][x_n] = cnt + 1
if flg == False:
    print(-1)

Fixed submission:
from collections import deque
 
 
def dfs(field):
    q = deque([(0, 0, 0)])
    visited = [[False] * w for _ in range(h)]
    while q:
        i, j, d = q.popleft()
        if i == h - 1 and j == w - 1:
            return d
        if visited[i][j]:
            continue
        visited[i][j] = True
        if i > 0 and field[i - 1][j] == '.':
            q.append((i - 1, j, d + 1))
        if i < h - 1 and field[i + 1][j] == '.':
            q.append((i + 1, j, d + 1))
        if j > 0 and field[i][j - 1] == '.':
            q.append((i, j - 1, d + 1))
        if j < w - 1 and field[i][j + 1] == '.':
            q.append((i, j + 1, d + 1))
    else:
        return -1
 
 
h, w = map(int, input().split())
field = [input() for _ in range(h)]
dot_cnt = sum(r.count('.') for r in field)
d = dfs(field)
if d == -1:
    print(-1)
else:
    print(dot_cnt - (d+1))

Buggy python submission (verdict: Time Limit Exceeded):
from queue import Queue
import itertools
import numpy as np

R, C = map(int, input().split())
sy, sx = 1, 1
gy, gx = R, C

field = [["#"] * (C + 2)] + \
        [list("#" + input() + "#") for i in range(R)] + \
        [["#"] * (C + 2)]
dxy = [(0,1), (0,-1), (1,0), (-1,0)]
flg = False
cnt = 0

field_1d = list(itertools.chain.from_iterable(field))
field01 = [1 if i == '.' else 0 for i in field_1d]
dot_num = np.array(field01).sum()

q = Queue()
q.put([sy, sx])
field[sy][sx] = 0

while flg == False:
    yx = q.get()
    cnt = field[yx[0]][yx[1]]
    for dy, dx in dxy:
        y_n, x_n = yx[0] + dy, yx[1] + dx
        if y_n == gy and x_n == gx:
            field[y_n][x_n] = cnt + 1
            flg = True
            print(dot_num - (cnt+2))
        if field[y_n][x_n] == '#':
            continue
        if field[y_n][x_n] == '.':
            q.put([y_n, x_n])
            field[y_n][x_n] = cnt + 1
if flg == False:
    print(-1)

Fixed submission:
from collections import deque
 
 
def dfs(field):
    q = deque([(0, 0, 0)])
    visited = [[False] * w for _ in range(h)]
    while q:
        i, j, d = q.popleft()
        if i == h - 1 and j == w - 1:
            return d
        if visited[i][j]:
            continue
        visited[i][j] = True
        if i > 0 and field[i - 1][j] == '.':
            q.append((i - 1, j, d + 1))
        if i < h - 1 and field[i + 1][j] == '.':
            q.append((i + 1, j, d + 1))
        if j > 0 and field[i][j - 1] == '.':
            q.append((i, j - 1, d + 1))
        if j < w - 1 and field[i][j + 1] == '.':
            q.append((i, j + 1, d + 1))
    else:
        return -1
 
 
h, w = map(int, input().split())
field = [input() for _ in range(h)]
dot_cnt = sum(r.count('.') for r in field)
d = dfs(field)
if d == -1:
    print(-1)
else:
    print(dot_cnt - (d+1))