f f a x a f f f x f a a a a 2.2 f f a x a f f x f a a a f f a x a f x f a a f f a x a f f f x f a a a a f f a x a f a a true f f a x a f f f x f a a a a f f a x a f f x f a a a true 2 1 a 0 1 1 f 2 0 0 1 0 1 0 0 1 0 2 3566 0 f 2 1 0 0 0 1 0 0 f f a x a f f f x f a a a a f f a x a f f f x f a a a a f f a x a f f f x f a a a a true 2 1 a 0 1 1 f 2 0 0 1 0 1 5969 0 f 2 1 0 0 0 1 0 0 f f a x a f f f x f a a a a f f a x a f x f a a false f f a x a f a a false NaTT certifiable-1.6