H,W = map(int,input().split())
s = [list(input()) for i in range(H)]
for i in range(H):
	for j in range(W):
		if s[i][j] == "#":
			if s[i-1][j] == "." and s[i+1][j] == "." and s[i][j-1] == "." and s[i][j+1] == ".":
			    print("No")
			    exit()
print("Yes") 