H, W = list(map(int, input().split()))

s = ['.' * (W+2)]
for i in range(H):
    s.append('.' + input() + '.')
s.append('.' * (W+2))

ans = True
for y in range(1, W+1):
    for x in range(1, H+1):
        if s[y][x] == '#':
            if '#' not in [s[y][x+1], s[y][x-1], s[y+1][x], s[y-1][x]]:
                ans = False
                break
    if not ans:
        break

if ans:
    print('Yes')
else:
    print('No')
