height,width = map(int, input().split())
map_list = []
for i in range(height):
    map_list.append(list(input()))
    map_list[i].append('0')
map_list.append(['0'] * width)

for h in range(height):
    for w in range(width):
        if map_list[h][w] == '#':
            if '#' in [map_list[h-1][w], map_list[h+1][w], map_list[h][w-1], map_list[h][w+1]]:

            else:
                print("No")
                exit()

print("Yes")
