H,W = map(int,raw_input().split())
S = range(H);ans = range(H);z = 0
for x in range(H):
	S[x] = map(str,raw_input())
	ans[x] = map(int,range(W))
	for y in range(W):
		if x > 0 and S[x][y] <> S[x-1][y] and y > 0 and S[x][y] <> S[x][y-1] and S[x][y] == '#':
			z += 1
print('No' if z >= 1 else 'Yes')