#!/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[ ]:




