H,W = map(int, input().split())
info = []
for i in range(W):
    info.append(list(input()))
    print (info)

counter = 0

def check(li,x,y):
    d = [-1,1]
    bool = False
    for dx in d:
        if x + dx >= 0 and x + dx < W and li[x + dx][y] == '#':
            bool = True
        else:
            pass
    for dy in d:
        if y + dy >= 0 and y + dy < H and li[x][y + dy] == '#':
            bool = True
        else:
            pass
    return bool


for x in range(W):
    for y in range(H):
        if info[x][y] == '#':
            if check(info,x,y) == False:
                counter += 1
                pass
        else:
            pass

if counter > 0:
    print ('No')
else:
    print ('Yes')