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

table = []

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


def check(x,y):
	if table[y-1][x]=='#' or table[y+1][x]=='#' or table[y][x-1]=='#' or table[y][x+1]=='#' :
		return
	else:
		print ('No')
		quit()
		

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

print ('Yes')		