h, w = map(int, input().split())
src = [input() for i in range(h)]
ans = []
for row in src:
    ans.append(list(row))
dxy = [(-1, 0), (0, 1), (1, 0), (0, -1)]
for y in range(h):
    for x in range(w):
        for dx, dy in dxy:
            if y + dy < 0 or y + dy > h - 1 or x + dx < 0 or x + dx > w - 1: continue
            if src[y][x] == '#' and src[y+dy][x+dx] == '#':
                ans[y][x] = 'b'
                ans[y+dy][x+dx] = 'b'

for row in ans:
    if row.count('#') > 0:
        print('No')
        exit()
    else:
        print('Yes')
        exit()