
h,w = map(int,input().split())

tab = []
for i in range(0,h):
    tab.append(input())

alone = True

#print(tab[h-1][w-1])
for hi in range(0,h):
    for wi in range(0,w):

        if tab[hi][wi] != '#':
            continue

        if hi + 1 < h:
            alone &= tab[hi + 1][wi] != '#'

        if hi - 1 >= 0:
            alone &= tab[hi - 1][wi] != '#'

        if wi + 1 < w:
            alone &= tab[hi][wi + 1] != '#'

        if wi - 1 >= 0:
            alone &= tab[hi][wi - 1] != '#'

#    if alone:
#        break
print("Yes" if not alone else "No")