h, w = map(int, input().split())
s = []
for i in range(h):
    s.append(input())

cnt = 0
for i in range(h):
    cnt += s[i].count('#')
if cnt == 0:
    print('Yes')
    exit()

flg = False
for i in range(h):
    for j in range(w):
        if (s[i][j] == '#'):
            if (i -1) >= 0:
                flg = (flg or (s[i - 1][j] == '#'))
            if (j - 1) >= 0:
                flg = (flg or (s[i][j - 1] == '#'))
            if (j + 1) < w:
                flg = (flg or (s[i][j + 1] == '#'))
            if (i + 1) < h:
                flg = (flg or (s[i + 1][j] == '#'))
            if not(flg):
                break
    if not(flg):
        break

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