
h, w = map(int, input().split())
s = [["." for _ in range(w + 2)]]

for _ in range(h):
    s_ = ["."]
    s_.extend([x for x in input()])
    s_.append(".")
    s.append(s_)

s.append(["." for _ in range(w + 2)])


for y in range(h):
    for x in range(w):
        target_x = x + 1
        target_y = y + 1
        # cross check
        if s[target_x][target_y]  == "#":
            if s[target_x - 1][target_y] == "#" or s[target_x + 1][target_y] == "#" or s[target_x][target_y -1 ] == "#" or  s[target_x][target_y +1 ] == "#":
                pass
                # ok
            else:
                # ng
                print("No")
                exit()
print("Yes")

