#下，右，上，左
dy = [1, 0, -1, 0]
dx = [0, 1, 0, -1]

H, W = map(int, input().split())
S = []
for i in range(H):
    S.append(list(input()))

flg = False

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

        if S[y][x] == ".":
            continue

        cnt = 0

        for k in range(4):
            ny = y + dy[k]
            nx = x + dx[k]

            if ny < 0 or ny >= H or nx < 0 or nx >= W:
                continue

            if S[ny][nx] == "#":
                flg = True
                break
        if flg:
            continue
        else:
            print("No")
            exit()

print("Yes")