h, w = map(int, input().split())
s = [list(input()) for _ in range(h)]
r = False
for i in range(h):
    for j in range(w):
        if s[i][j] == ".":
            pass
        elif 0 <= (i - 1) and s[i - 1][j] == "#":
            r = True
        elif (i + 1) < h and s[i + 1][j] == "#":
            r = True
        elif 0 <= (j - 1) and s[i][j - 1] == "#":
            r = True
        elif (j + 1) < w and s[i][j + 1] == "#":
            r = True
        else:
            r = False
            break
    if r == False: break


print("Yes") if r else print("No")
