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

ds = [(1, 0), (-1, 0), (0, 1), (0, -1)]

for i in range(H):
    for j in range(W):
        if S[i][j] == ".":
            continue

        flag = False
        for dx, dy in ds:
            x, y = i + dy, j + dx
            if x < 0 or W <= x or y < 0 or H <= y:
                continue

            if S[x][y] == "#":
                flag = True
                break

        if not flag:
            print("No")
            exit()
print("Yes")
