H, W = map(int, input().split())
s = ["".join(["0"]*(H+2))] + ["0"+input()+"0" for _ in range(H)] + ["".join(["0"]*(H+2))]
failed = False
for i in range(1, W+1):
    for j in range(1, H+1):
        if '#' != s[i][j]:
            continue
        if '#' in [s[i+x][j+y] for x, y in [(0, -1), (-1, 0), (1, 0), (0, 1)]]:
            continue
        else:
            failed = True
            break
    if failed:
        print("No")
        break
else:
    print("Yes")
