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

s0 = ['.'*w]
S = s0 + s + s0
L = [0]*(h+2)

for i in range(h+2):
    l = '.' + S[i] + '.'
    L[i] = l

ans = True
cnt = 0
for i in range(1, w+2):
    for j in range(1, h+2):
        cnt = 0
        if L[i][j] == '#':
            if L[i+1][j] == '#':
                cnt += 1
            elif L[i-1][j] == '#':
                cnt += 1
            elif L[i][j+1] == '#':
                cnt += 1
            elif L[i][j-1] == '#':
                cnt += 1
            if cnt == 0:
                ans = False
                break

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

