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

for i in range(h):
    for j in range(w):
        if s[i][j] == '.':
            continue
        if i-1 > 0 and s[i-1][j] == '#':
            continue
        if i+1 < h and s[i+1][j] == '#':
            continue
        if j-1 > 0 and s[i][j-1] == '#':
            continue
        if j+1 < w and s[i][j+1] == '#':
            continue
        print('No')
        break
    else:
      continue
    break
else:
    print('Yes')