f f a x a f a f f a f a a x 2.2 f f a x a f f a f a a x f f a x a f a f a a f f a x a f a f f a f a a x f f a x a f a a true f f a x a f f a f a a x true 2 1 a 0 1 21657 f 2 0 0 1 0 2 25907 21656 f 2 1 1 1 1 1 0 0 1 1 2 0 0 f f a x a f a f f a f a a x f f a x a f a f f a f a a x false f f a x a f a f a a false f f a x a f a a false NaTT certifiable-1.6