H, W = map(int, input().split())
M = ['.' * (W+2)]
for _ in range(H):
    M.append('.' + input() + '.')
M.append('.' * (H+2))
flag = True
for i in range(1, H+1):
    for j in range(1, W+1):
        if M[i][j] == '#':
            if '#' not in (M[i+1][j], M[i][j+1], M[i-1][j], M[i][j-1]):
                flag = False
if flag:
    print('Yes')
else:
    print('No')