h, w = map(int, input().split())
s = [list(input()) for _ in range(h)]
ans = True

for i in range(h):
    for k in range(w):
        count =True
        if s[i][k] == ".":
            break

        d = [[0, 1], [1, 0], [0, -1], [-1, 0]]
        for l in d:
            if 0 <= i + l[0] < h and 0 <= k + l[1] < w:
                if s[i + l[0]][k + l[1]] == "#":
                    count = False

        if count:
            ans = False

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