f f f a f a a a x f x f x a 2.2 f f f a f a a a x f x a f f f a f a a a x f x f x a true f f f a f a a a x f x f x a f f f a f a a a x f x a true a 0 1 f 2 8367 f 2 1 2 0 f f f a f a a a x f x f x a f f f a f a a a x f x f x a f f f a f a a a x f x f x a true Failed! NaTT certifiable-1.6