def inpl(): return list(map(int, input().split()))
H, W = inpl()
s = ['.'*(W+2)]
for i in range(H):
    s.append('.'+input()+'.')
s.append('.'*(W+2))

end = 0
dxy = [[1,0],[0,1],[-1,0],[0,-1]]
for i in range(1,H+1):
    for j in range(1,W+1):
        for k in dxy:
            if s[i+k[0]][j+k[1]]=='#':
                break
        else:
            end = 1
            break
    if end == 1:
        break
if end == 1:
    print('No')
else:
    print('Yes')