f f a f a a x f x f f a a a 2.2 f f a f a a x f f a a a f f a f a a x f x f f a a a true f f a f a a x f x f f a a a true a 0 0 f 2 1 11799 2 23599 0 f 2 1 8856 2 8857 0 f f a f a a x f x f f a a a f f a f a a x f f a a a false NaTT certifiable-1.6