H, W = map(int, input().split())
s = ['.' + input() +'.' for _ in range(H)]
s = ['.'] * (W + 2) s + ['.'] * (W + 2)
flag = True
for h in range(1, H + 1):
    for w in range(1, W + 1):
        if (s[h][w] == '#' and s[h - 1][w] == '.' and s[h + 1][w] == '.'
               and s[h][w - 1] == '.' and s[h][w + 1] == '.'):
            flag = False
                
print('Yes' if flag else 'No')
