H, W = map(int, input().split())
G = []
for i in range(H):
    G.append(list(input()))
ans = "Yes"
if H == 1 and W == 1:
    if G[0][0] == '#':
        print('No')
        exit()
    else:
        print('Yes')
        exit()
for i in range(H-1):
    for j in range(W-1):
        boo = True
        if G[i][j] == '#':
            if G[i][j+1] == '#' and j+1 < W:
                boo = True
            elif G[i][j-1] == '#' and j-1 > 0:
                boo = True
            elif G[i+1][j] == '#' and i+1 < H:
                boo = True
            elif G[i-1][j] == '#' and i-1 > 0:
                boo = True
            else:
                boo = False
        if not boo:
            ans = "No"
            break
print(ans)