Buggy python submission (verdict: Runtime Error):
#!/usr/bin/env python
# coding: utf-8

# In[2]:


H, W = map(int, input().split())
data = [["a"]*(W+2)]
for i in range(H):
    data.append(list("a" + input() + "a"))
data.append([["a"]*(W+2)])
# print(data)


# In[5]:


for h in range(H+1):
#     print(data[h])
    for w in range(W+1):
#         print(data[h][w])
        if data[h][w] == "#":
            if data[h-1][w] != "#" and data[h+1][w] != "#" and data[h][w-1] != "#" and data[h][w+1] != "#":
                print("No")
                exit()

print("Yes")


# In[ ]:






Fixed submission:
#!/usr/bin/env python
# coding: utf-8

# In[2]:


# H, W = map(int, input().split())
# data = [["a"]*(W+2)]
# for i in range(H):
#     data.append(list("a" + input() + "a"))
# data.append([["a"]*(W+2)])
# # print(data)


# In[5]:


# for h in range(H+1):
# #     print(data[h])
#     for w in range(W+1):
# #         print(data[h][w])
#         if data[h][w] == "#":
#             if data[h-1][w] != "#" and data[h][w-1] != "#" and data[h][w+1] != "#" and data[h+1][w] != "#":
#                 print("No")
#                 exit()

# print("Yes")


# In[ ]:


h, w = map(int, input().split())
s = [["a"]*(w + 2)]
 
for i in range(h):
    s.append(list("a" + input() + "a"))
s.append(["a"]*(w + 2))
 
for i in range(h + 1):
    for j in range(w + 1):
        if s[i][j] == "#":
            if s[i - 1][j] != "#" and s[i][j - 1] != "#" and s[i][j + 1] != "#" and s[i + 1][j] != "#":
                print("No")
                exit()
 
print("Yes")

Buggy python submission (verdict: Runtime Error):
#!/usr/bin/env python
# coding: utf-8

# In[2]:


H, W = map(int, input().split())
data = [["."]*(W+2)]
for i in range(H):
    data.append(list("." + input() + "."))
data.append([["."]*(W+2)])
# print(data)


# In[5]:


flag = 0
for h in range(H+1):
#     print(data[h])
    for w in range(W+1):
#         print(data[h][w])
        if data[h][w] == "#":
            if data[h-1][w] != "#" and data[h+1][w] != "#" and data[h][w-1] != "#" and data[h][w+1] != "#":
                flag = 1
                break

if flag == 1:
    print("No")
else:
    print("Yes")


# In[ ]:






Fixed submission:
#!/usr/bin/env python
# coding: utf-8

# In[2]:


# H, W = map(int, input().split())
# data = [["a"]*(W+2)]
# for i in range(H):
#     data.append(list("a" + input() + "a"))
# data.append([["a"]*(W+2)])
# # print(data)


# In[5]:


# for h in range(H+1):
# #     print(data[h])
#     for w in range(W+1):
# #         print(data[h][w])
#         if data[h][w] == "#":
#             if data[h-1][w] != "#" and data[h][w-1] != "#" and data[h][w+1] != "#" and data[h+1][w] != "#":
#                 print("No")
#                 exit()

# print("Yes")


# In[ ]:


h, w = map(int, input().split())
s = [["a"]*(w + 2)]
 
for i in range(h):
    s.append(list("a" + input() + "a"))
s.append(["a"]*(w + 2))
 
for i in range(h + 1):
    for j in range(w + 1):
        if s[i][j] == "#":
            if s[i - 1][j] != "#" and s[i][j - 1] != "#" and s[i][j + 1] != "#" and s[i + 1][j] != "#":
                print("No")
                exit()
 
print("Yes")

Buggy python submission (verdict: Runtime Error):
#!/usr/bin/env python
# coding: utf-8

# In[2]:


H, W = map(int, input().split())
data = [["."]*(W+2)]
for i in range(H):
    data.append(list("." + input() + "."))
data.append([["."]*(W+2)])
# print(data)


# In[5]:


flag = 0
for h in range(H+1):
#     print(data[h])
    for w in range(W+1):
#         print(data[h][w])
        if data[h][w] == "#":
            if data[h-1][w] != "#" and data[h+1][w] != "#" and data[h][w-1] != "#" and data[h][w+1] != "#":
                flag = 1

if flag == 1:
    print("No")
else:
    print("Yes")


# In[ ]:






Fixed submission:
#!/usr/bin/env python
# coding: utf-8

# In[2]:


# H, W = map(int, input().split())
# data = [["a"]*(W+2)]
# for i in range(H):
#     data.append(list("a" + input() + "a"))
# data.append([["a"]*(W+2)])
# # print(data)


# In[5]:


# for h in range(H+1):
# #     print(data[h])
#     for w in range(W+1):
# #         print(data[h][w])
#         if data[h][w] == "#":
#             if data[h-1][w] != "#" and data[h][w-1] != "#" and data[h][w+1] != "#" and data[h+1][w] != "#":
#                 print("No")
#                 exit()

# print("Yes")


# In[ ]:


h, w = map(int, input().split())
s = [["a"]*(w + 2)]
 
for i in range(h):
    s.append(list("a" + input() + "a"))
s.append(["a"]*(w + 2))
 
for i in range(h + 1):
    for j in range(w + 1):
        if s[i][j] == "#":
            if s[i - 1][j] != "#" and s[i][j - 1] != "#" and s[i][j + 1] != "#" and s[i + 1][j] != "#":
                print("No")
                exit()
 
print("Yes")

Buggy python submission (verdict: Runtime Error):
#!/usr/bin/env python
# coding: utf-8

# In[2]:


H, W = map(int, input().split())
data = [["."]*(W+2)]
for i in range(H):
    data.append(list("." + input() + "."))
data.append([["."]*(W+2)])
# print(data)


# In[3]:


data


# In[5]:


flag = 0
for h in range(H+1):
#     print(data[h])
    for w in range(W+1):
#         print(data[h][w])
        if data[h][w] == "#":
            if data[h-1][w] != "#" and data[h+1][w] != "#" and data[h][w-1] != "#" and data[h][w+1] != "#":
                flag = 1

if flag == 1:
    print("No")
else:
    print("Yes")


# In[ ]:






Fixed submission:
#!/usr/bin/env python
# coding: utf-8

# In[2]:


# H, W = map(int, input().split())
# data = [["a"]*(W+2)]
# for i in range(H):
#     data.append(list("a" + input() + "a"))
# data.append([["a"]*(W+2)])
# # print(data)


# In[5]:


# for h in range(H+1):
# #     print(data[h])
#     for w in range(W+1):
# #         print(data[h][w])
#         if data[h][w] == "#":
#             if data[h-1][w] != "#" and data[h][w-1] != "#" and data[h][w+1] != "#" and data[h+1][w] != "#":
#                 print("No")
#                 exit()

# print("Yes")


# In[ ]:


h, w = map(int, input().split())
s = [["a"]*(w + 2)]
 
for i in range(h):
    s.append(list("a" + input() + "a"))
s.append(["a"]*(w + 2))
 
for i in range(h + 1):
    for j in range(w + 1):
        if s[i][j] == "#":
            if s[i - 1][j] != "#" and s[i][j - 1] != "#" and s[i][j + 1] != "#" and s[i + 1][j] != "#":
                print("No")
                exit()
 
print("Yes")