h,w=map(int,input().split())
s=[]
s.append("."*(h+2))

for i in range(w):
    s.append("."+input()+".")
    
s.append("."*(h+2))

for i in range(1,w+1):
    for j in range(1,h+1):
        #print(i,j)
        if s[i][j]=="#":
            if s[i][j+1]=="#" or s[i][j-1]=="#" or s[i+1][j]=="#" or s[i-1][j]=="#":
                pass
            else:
                print("No")
                exit()
        

print("Yes")