h,w=sorted(map(int, input().split()))
s= ["."+input()+"." for _ in range(h)]
t=".."
for i in range(w):
    t+="."
s.insert(0,t)
s.append(t)
ans=0
for i in range(h):
    for j in range(w):
        if s[i+1][j+1]=="#":
            if s[i][j+1]=="." and s[i+1][j]=="." and s[i+1][j+2]=="." and s[i+2][j+1]==".":
                ans+=1
print("Yes" if ans==0 else "No")