import sys
H,W = input().split()
H = int(H)
W = int(W)
s = []

s.append("."*(W+2))
for i in range(H):
    s.append("."+input()+".")

s.append("."*(W+2))


for j in range(1,1+H):
    for i in range(1,1+W):
#        print(j,i)
        if s[i][j] == "#":
            if s[i][j-1] != "#" and s[i][j+1] != "#" and s[i-1][j] != "#" and s[i+1][j] != "#":
                print("No")

                sys.exit()

print("Yes")
