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

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

field = []

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

for y in range(H):
    for x in range(W):
        
        if field[y][x] == ".":
            continue

        for k in range(4):

            cnt = 0

            ny = y + dy[k]
            nx = x + dx[k]

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

            elif field[ny][nx] == "#":
                cnt += 1

        if cnt == 0:
            print("No")
            exit()

print("Yes")