times x y sum generate x y generate x y gen x y 0 gen x y z if ge z x x y z if true x y z nil if false x y z cons y gen x y s z sum nil 0 sum cons 0 xs sum xs sum cons s x xs s sum cons x xs ge x 0 true ge 0 s y false ge s x s y ge x y 2.2 ge s x s y ge x y gen x y z ge z x sum cons s x xs sum cons x xs times x y sum generate x y gen x y z if ge z x x y z sum cons 0 xs sum xs generate x y gen x y 0 times x y generate x y if false x y z gen x y s z true times x y generate x y false generate x y gen x y 0 false if false x y z gen x y s z gen x y z if ge z x x y z true Failed! NaTT certifiable-1.6