a =str(input()).split(" ")
h = int(a[0])
w = int(a[1])
maps= []

for i in range(h):
    maps.append(list(input()))
   
for i in range(h-1):
    for j in range(w):
        if maps[i][j] == "#":
            if maps[i][j - 1] == "#" and j - 1 > 0:
                continue
            elif maps[i][j + 1] == "#" and j + 1 < w:
                continue
            elif maps[i + 1][j] == "#" and i + 1 < h:
                continue
            elif maps[i - 1][j] == "#" and i - 1 > 0:
                continue
            else:
                print("No")
                exit()
        else:
            pass

print("Yes")
