H,W = map(int, input().split())

table = []

for i in range(H):
	table.append(list(input()))

counter = 0
	
def check(x,y):
	counter = 0
	if x > 0:
		if table[y][x-1] == '#':
			counter += 1
			
	if x >= W:
		if table[y][x+1] == '#':
			counter += 1
	
	if y > 0:
		if table[y-1][x] == '#':
			counter += 1
	
	if y >= H:
		if table[y+1][x] == '#':
			counter += 1
	
	if counter == 0:
		print('No')
		quit()
			
	

for y in range(H):
	for x in range(W):
		check(x,y)

print ('Yes')	