h,w=map(int, input().split())
s=['.'*w]
for _ in range(h):
    s.append('.'+input()+'.')
s.append('.'*w)
    
# 全ての#マスにおいて、縦横のいずれかが#であればOK
for i in range(h):
    for j in range(w):
        if s[i][j]=="#":
            if s[i-1][j] == s[i+1][j] == s[i][j-1] == s[i][j+1] == ".":
                print("No")
                #exit()
print("Yes")
    
    